Four explosions in Columbia and Ellicott City Friday night and early yesterday morning damaged two cars, a home and a mailbox but caused no injuries, police said.
The last of the blasts -- at 4:15 a.m. yesterday -- did the most damage, crashing in the door and damaging the siding of an Ellicott City home.
"It was described to me as looking like someone beat the door in with a battering ram," Howard County Police Lt. Samuel Chayt said.
Bob Thomas, spokesman for the state fire marshal, said bomb squad investigators have determined that the last two explosions were caused by pipe bombs, each 6 inches long and 2 inches wide. He said it was not yet clear what type of devices caused the first two explosions.
The four blasts occurred within a 3-mile radius, but police had established no firm link among the four explosions. No suspects have been arrested, Mr. Thomas said.
He said the first explosion occurred at 9 p.m. Friday in the parking lot of the Palace Nine Theater near Center Park Drive in Columbia. He said he could not confirm any damage from this blast.
But Lieutenant Chayt said his department received a report of an explosive device placed under the hood of a 1985 Ford Thunderbird in the theater lot. The explosion buckled the hood and blew out the windshield, he said.
About 15 minutes later, a mailbox blew up in the Glenmont development in Columbia, about three-quarters of a mile from the theater, Lieutenant Chayt said. Mr. Thomas said his agency could not confirm the location of or the damage from the second blast.
"I'm guessing these two are related because of the proximity" in time and distance, Lieutenant Chayt said.
At 11:38 p.m., a pipe bomb exploded beneath a 1992 Mercury parked in the 5700 block of Yellow Rose Court in Columbia, Lieutenant Chayt said. The car burst into flames and the tires were flattened. He said that street is about 1 1/2 miles from Glenmont. This seemed to be a more powerful explosion than the first two, he said, and did "considerable damage" to the car.
The last explosion was in the 5500 block of Foxtail Lane in Ellicott City, where a pipe bomb was placed on a front porch. The blast woke the owner of the home, a 43-year-old man, who was the only person at home at the time. Police said they were not releasing the man's name to protect him. The explosion pushed in the front door, blew out the front window and damaged the siding.
Mr. Thomas said his investigators recovered "90 percent" of the two pipe bombs but had established no link between the victims of those two explosions.
Lieutenant Chayt said: "It appears to be completely random at this point. We are just not sure why these locations were selected."