Police said it was too early to say whether the snowy, icy conditions played a role in either incident.
A MARC train hit an SUV at a grade crossing at Hollins Ferry Road near Paca Street about 6:20 a.m., said Det. Jeremy Silbert, a Baltimore police spokesman. The driver of the vehicle, Morgan Fleet, 23, was pronounced dead at the scene, and Wayne Burnett Jr., the 38-year-old passenger died later at a hospital.
Separately, a 50-year-old woman was hit by a Charm City Circulator bus about 10:30 a.m. Tuesday at North Wolfe and East Monument streets near Johns Hopkins Hospital, police said. The woman was not immediately identified.
"It's too early ... to determine whether weather had anything to do with either incident," Silbert said.
The 800 block of E. Monument St. was closed Tuesday afternoon while officers from the Police Department's accident investigation unit examined the scene of the pedestrian death.
The incident involved a Green-line bus that runs from City Hall to Fells Point to Johns Hopkins Hospital. The bus remained parked behind police crime tape for several hours as investigators surveyed the scene. The woman's body lay under a blue tarp behind the left-rear wheel. Police believe the bus ran over the woman, Silbert said.
Silbert did not know how many passengers were on the bus, but said none of its occupants were injured.
In the MARC collision, no injuries were reported among the 20 passengers on board the train, which departed at 6:10 a.m. Tuesday headed to Washington's Union Station. Baltimore police are investigating the crash, with assistance from Amtrak police.
It had not begun snowing in downtown Baltimore at the time of the crash, though conditions in the region were still icy and snowy from Sunday's storm.
The crossing where the crash occurred is the second-most dangerous in Maryland, according to the Federal Railroad Administration. There is about a 15 percent chance of a crash at that crossing in any given year, according to a formula the agency uses to calculate the likelihood.
About 42 trains — MARC and CSX — pass through the gated crossing every day at an average speed of 50 mph, according to the railroad administration. Since 2008, two other crashes have been reported at the crossing; no one was injured.
"While investigators have not yet determined a cause of [the] horrible crash, it is a tragic reminder of the dangers of a motor vehicle and train collision," Ragina C. Averella, a spokeswoman for AAA Mid-Atlantic, said in an email. "Unfortunately, motorists are 40 times more likely to die from injuries sustained in a crash with a train than in a collision with another motor vehicle."
More than 300 people are killed in crashes between trains and vehicles each year around the country, Averella said. Freight trains carrying a typical load can weigh 4,000 to 8,000 tons, she said.
"Understandably, the damage that can be inflicted on a motor vehicle by such a train can be absolutely catastrophic," she said.
To calculate the likelihood of a collision, the railroad administration uses a formula that takes into account factors such as the number of daily trains, the history of collisions, and the type and number of safety devices in place.
The most dangerous crossing in Maryland is on Randolph Road in Rockville, where the chances of a crash in any given year are nearly 30 percent.
Paul Shepard, a spokesman with the Maryland Transit Administration, told The Washington Post that initial reports indicated that the vehicle "went around" a gate at the crossing and was struck by the train. He said MARC ridership was "extremely light" Tuesday because federal government offices were closed.
The Hollins Ferry Road railroad crossing is gated, and a picture posted to Twitter by an ABC2 reporter shortly after the crash showed the gate was down.
Railroad crossing gates rarely malfunction, said Russ Quimby, a former National Transportation Safety Board investigator who is now a railroad safety consultant in Omaha, Neb.
"Those signals are extremely reliable and rugged, and they work in all kinds of weather," Quimby said.
About a quarter of the fatal crashes between vehicles and trains in the United States take place at gated crossings, Quimby said.
"Some people get impatient, particularly if they're on their way to work," he said. "One of the reasons that almost all railroads have installed video cameras is because of grade crossing accidents. It saves them thousands, if not millions, of dollars in lawsuits."
Making rail crossings elevated removes the risk, as is the case with Amtrak's Northeast Corridor lines, Quimby said. Crossings also can be made safer by adding longer cross arms and medians to keep drivers from cutting through when the gates are down, but Quimby said those upgrades could cost millions of dollars per crossing.