A commuter train traveling near Bowie yesterday pulled down the overhead electrical lines that power Amtrak and Maryland Commuter Rail Service (MARC) trains, blocking service between Washington and Baltimore for almost three hours and delaying thousands of passengers throughout the Northeast corridor.

The MARC train was traveling from Washington's Union Station to Baltimore at 7:25 a.m. when its pantagraph, the device that collects electrical current from the power lines, slipped and pulled down three wires, said MARC and Amtrak spokesmen. No one was injured, they said.

The wires blocked and cut off power to all three parallel tracks until 10:15 a.m., when one track was opened, said Amtrak spokesman R. Clifford Black. The other two were opened by 11:20 a.m., he said.

The accident delayed about a dozen Amtrak trains and three MARC trains, affecting more than 3,000 passengers, the spokesmen said. Four Amtrak trains were canceled.

Amtrak provided bus service between Washington and Baltimore while the tracks were blocked. Two northbound trains traveling from the South were held at Union Station while repairs were made. Southbound trains headed to Union Station were turned around in Baltimore for northbound service.

Amtrak trains suffered minor delays long after the track was cleared because of disruptions in the scheduled movement of equipment, Black said.