Two-foot deep crater left by explosion on SEPTA overpass

A freak explosion on a train overpass in Strawberry Mansion left a two-foot-deep crater and caused a 37-minute halt to trains on two SEPTA Regional Rail lines Friday evening, authorities said.

"The bomb squad was called and determined that ... there was an explosion of some kind creating a roughly two-foot deep crater," Mayor Nutter's spokesman Mark McDonald said. "Police radio learned there were two males that were picked up by EMS in the area of the bridge and taken to Saint Joseph's Hospital with minor injuries, scrapes and cuts, injuries that possibly you might see with an explosion."

The explosion on the 3000 block of Cecil B. Moore Avenue was caused not by a device but by a "thermic reaction," likely when an icicle broke off and hit a power line, said Chief Inspector Joseph Sullivan, of the city police homeland security department.

City police and Amtrak sent bomb-sniffing dogs to the scene. "There was zero evidence of the presence of explosives," Sullivan said.

"It was a powerful explosion," Sullivan said. "It blew chunks of concrete across the street."

An SUV driving nearby was hit by debris. The vehicle's two occupants asked to be taken to Temple University Hospital as a precaution, Sullivan said.

Trains on the Chestnut Hill West and Trenton Regional Rail lines were shut down for 37 minutes from 6 to 6:37 p.m., according to an Amtrak spokesman. The four tracks that run from 30th Street Station to Trenton are owned by Amtrak, which stopped all service for the short time after the explosion, which police said occurred on the street bridge that goes over the tracks at 31st Street and Cecil B. Moore Avenue.

No damage was done to the train tracks under the bridge and no debris was found below, McDonald said.

"An explosion of this magnitude is unusual," Sullivan said. "An event of this nature is not."

Philadelphia police initially said a possible underground transformer explosion rocked the road overpass at the intersection at about 5 p.m. and weakened the structural integrity of the bridge.

The tracks are along the Northeast Corridor system connecting cities from Washington to Boston.

Automotive traffic in the area was blocked for several hours.