As rescue workers continued to search yesterday for three missing passengers of the Seaport Taxi overturned by a vicious storm Saturday, federal investigators questioned the captain, first mate and other survivors, trying to learn more about the fatal capsizing in Baltimore harbor.

Investigators from the National Transportation Safety Board were trying to ascertain, among other things, why word of a rapidly moving thunderstorm did not reach the 36-foot pontoon boat before it left its dock at Fort McHenry. Strong warnings from weather officials about the sudden storm arrived only as the boat had started its trip across the harbor, advisory reports show.

Also yesterday, authorities said that the 2-ton boat, while smaller than some water taxis in use on the harbor, was permitted by safety regulations to run a route across the harbor to Fort McHenry.

With investigators piecing together the details of the the first fatal accident involving a water taxi on the Inner Harbor, the hunt for the missing continued.

When the accident occurred, rescuers from a Naval Reserve base at the fort and a Fire Department boat pulled 22 people from the water, including a 60-year-old woman who died. Officials were still waiting to release her identity yesterday.

The missing are 6-year old Daniel Benstrem, of Harrisonburg, Va., who was on an outing with his family, and Corinne J. Schillings, 26, of Homewood, Ill., and her fiance, Andrew M. Roccella, also 26, of Virginia.

Baltimore fire and police searched throughout the day, using sonar equipment and divers to scan the bottom of the harbor, before halting their efforts at 6 p.m. because of darkness. The search is to resume this morning.

Schillings and Roccella were engaged to be married and had brought their families together for a weekend in Baltimore, according to neighbors in Roccella's parents' Vienna, Va., neighborhood.

Edward and Eileen Roccella and Karen and Denny Schillings were also on the water taxi when it capsized.

The missing little boy, Daniel Bentrem, was vacationing in Baltimore with his parents, George and Elizabeth Bentrem and his two older sisters.

While waiting for word of their son, the Bentrems were watching over their 8-year-old daughter, Sarah, who remained in critical condition at Maryland Shock Trauma Center, said Karim Altaii, a neighbor who drove to Baltimore on Saturday night to be with them.

The family's third child, a 7-year-old girl who was also on the boat, is safe, he said.

Altaii said the Bentrems had been planning to visit Baltimore the previous weekend but postponed it one week because of the weather - a cruel irony in hindsight, he noted.

"George was so excited about taking the kids there and spending quality time with them," Altaii said. George Bentrem is a general practice physician with an office in Broadway, Va.

One other survivor remains in critical condition, a 30-year-old woman, said Fire Department Chief William J. Goodwin Jr. Four other survivors remained in noncritical condition at area hospitals, officials said.

Of the 25 people on the boat, 12 were from Virginia, four were from Maryland, three each were from New Jersey and Illinois, two were from North Carolina and one was from Puerto Rico, officials said.

The Coast Guard had repeatedly inspected and certified the boat, called the Lady D, and granted it a license to cruise out to the fort in March 2003 - a license still valid at the time of the accident, according to records and Lt. Andrew Ely, a spokesman for the Coast Guard. The Coast Guard had approved the boat for 25 passengers, which was the number on board when it capsized, Ely said.

"This vessel was not out on the open ocean. It was on the Inner Harbor, and it has a license to operate in this area," Ely said. "If they had asked, 'Can we take 25 passengers across the ocean?' the answer would have been no. But it was on the Chesapeake Bay, where it was authorized to be."

What remained unanswered one day after the accident was whether the boat's captain, weather forecasters or marine authorities could have better foreseen the force of the fast-moving, freakish storm that raced over the city in the midst of a mild afternoon and caught the vessel just as it was leaving its dock at the fort to cross the harbor to Fells Point.

The taxi was about 100 yards from shore and trying to turn back toward the dock at the fort about 4 p.m. when winds gusting as high as 45 mph flipped it over, tossing the 25 people into 44-degree waters.

NTSB investigators spent much of the day interviewing the boat's captain, Francis Deppner, 74, a retired Army major from Middle River, at the Fells Point campus of the Living Classrooms Foundation, the nonprofit organization that owns and operates Seaport Taxi, one of two taxi services in the Inner Harbor.

Deppner declined to answer reporters' questions but released a statement through Living Classrooms President James Piper Bond: "I and everyone at the Seaport Taxi organization are deeply saddened by the tragedy that occurred yesterday afternoon aboard the Seaport Taxi Lady D."

He added, "I would like to extend my sincere concern and condolences to the passengers and families affected by yesterday's accident."

A Vietnam War veteran who served in the Army for 28 years, Deppner received his Coast Guard license in April 2002 and became a captain for Seaport Taxi that July.

He voluntarily submitted to blood and urine tests after the capsizing, and first mate Michael Homan submitted to blood tests, said NTSB Chairwoman Ellen Engleman-Conners. Officials were still awaiting results last night.

According to police, Deppner has told authorities that he had just called the Coast Guard to report the number of passengers and his destination of Fells Point when the sudden storm swept in. Much of yesterday's discussion of the capsizing revolved around whether Deppner or anyone else should have anticipated the force of the storm and ordered the boat docked.

A small-craft advisory had been issued Friday afternoon and remained in effect throughout the time of the capsizing. Bond said the service's taxis went out Saturday anyway because the boats are designed to handle the 20-knot winds warned of in the advisory.

But the storm that raced across the city just as the boat was leaving the fort was of an entirely different magnitude. At 3:58 p.m., the National Weather Service warned of thunderstorms with gusts up to 45 mph.

At 4:05 - four minutes after the first 911 call from a witness reporting the capsizing - the weather service issued its strongest warning, telling boats to get off the water.

Andy Woodcock, a National Weather Service forecaster based at Sterling, Va., said yesterday that the service will try to determine whether it could have gotten an emergency warning out sooner.

"Perhaps the special marine warning should have been issued earlier, but I wasn't sitting at the radar screen," Woodcock said. "I know our people were working very hard."

A former competitor of Seaport Taxi, Ron Morgan of the now-defunct Harbor Shuttle, has criticized Living Classrooms for using a 36-foot craft to make the trip to the fort.

"It was unsafe to put that boat out there," said Morgan, the former owner of the Lady D whose former collaboration with the foundation on Seaport shuttle operations ended in bitterness and a failed lawsuit. "That Lady D was not designed to go out to Fort McHenry. It was too low to the water. This kind of boat has no keel, so in the wind they are very hard to handle."

Bond, the Living Classrooms president, disagreed, saying his organization for the past six years has been using a slightly smaller boat than other services have used to go out to Fort McHenry because Living Classrooms takes a route that is half as long, from Fells Point rather than from Harborplace.

"The Coast Guard inspected the boat and approved it for that use," said Bond.

Coast Guard officials concurred yesterday, saying they knew about the size of the boats being used by the foundation and the route they were taking, and saw no problems.

The capsized boat was turned upright at 3:45 p.m. yesterday with the help of a hook attached to a large crane that hoisted the vessel out of the water.

The boat's canopy was missing, but the steering wheel and motor seemed to be intact, as were stairs on the forward area of the vessel used for climbing from the boat to the dock. The boat was later towed to an unspecified location for further examination by the NTSB.

Engleman-Conners said investigators were focusing on three areas of the boat: the condition of the hull, the steering and the propulsion. "The steering appeared to be normal," she said.

Investigators had also asked for construction designs from the boat's manufacturer, Susquehanna Santee Boatworks, to see if the vessel had been modified. Engleman-Conners discounted a report that a stabilizing device was missing from the boat.

Engleman-Conners said investigators had conducted lengthy interviews with Deppner, the captain, and the mate Homan, as well as with several passengers.

Deppner's interview lasted for several hours on the waterfront campus of Living Classrooms on South Caroline Street. The organization trains at-risk youth as shipmates on the taxis, but Homan, the mate Saturday, is a licensed captain.

Credit continued to be heaped yesterday on the rescuers who kept the toll from being higher than it was.

Several Navy reservists saw the accident, and immediately sailors rushed to a steel landing craft.

Within minutes, they reached the taxi. About 15 people had climbed atop the capsized boat; others were hanging from the side and floating nearby. The reservists threw a rope to the taxi and pulled the boats close together. Those on top of the taxi climbed aboard the Navy vessel or were carried.

The reservists said people were trapped beneath the taxi, and the reservists maneuvered their landing ramp under the taxi to lift it up. They found three people in the water. A woman and child were rescued, but a man was swept away.

"It's hard to think about that," said reservist Petty Officer 2nd Class Jeffrey King of Upperco. "We might have lost one, but we saved two. At that time, there were only two of us in the water, and that current was so bad. It was just banging us against the ship."

"I don't feel like a hero," he added. "We did the best we could. We saved lives that probably wouldn't have been saved."

Seaport Taxi, which averages more than 200,000 riders per year, has canceled service for today and will decide today whether to resume taxi rides tomorrow. Bond was unwilling yesterday to talk about the capsizing's possible effect on the future of the service.

"We're taking it one day at a time," he said.

Sun staff writers Scott Calvert, Tricia Bishop, Cyril T. Zaneski, Rona Kobell, Stephanie Hanes, Gail Gibson and Lynn Anderson contributed to this article.