Source: Abandoned wire laid by Pennsylvania RR in 1932 caused underground explosion at 30th&Market. Amtrak called. pic.twitter.com/6ajjbAM11Y— Jeff Chirico (@JeffChirico) May 22, 2016
It is likely abandoned, but still live, sources say, and for some reason it began burning about 8 feet under the street.
Sources say the wire is in a room or "vault" under the street that filled with gases when the wire burned. The build-up of gases caused the explosion.
Police were called to an underground fire after several reports of a loud bang in the University City section of Philadelphia.
Emergency crews blocked off the 2900 block of Market Street minutes after an explosion around 1 p.m. Saturday.
Firefighters arrived to find smoke coming from the street, and one manhole cover displaced.
"We were on 30th Street turning left onto Market when all of a sudden the road exploded," said Barbara Bersin of Northeast Philadelphia.
"We heard a big boom and looked up in the air, and the manhole cover was 20 feet in the air," said Daniel Solis of Center City.
Chunks of concrete rained down, fortunately missing pedestrians and cars. The blast created a large hole over the spot Solis had just passed with his wife.
"By the grace of God the light had just turned and we had crossed," said Solis. "Otherwise we'd have been standing on the manhole cover, and been hurt by the shrapnel."
Solis says passerby ran from the scene, fearing the blast was actually gunfire.
SEPTA buses were temporarily rerouted as PECO crews responded, and rail service was affected for about 20 minutes.
Witnesses, including SEPTA cashiers who work underground, say the incident could have been far worse.
"Thank God no one was hurt, but it's pretty scary to know we're underground and this is up top," said Michelle Goodman Hooper, SEPTA worker.
Amtrak was called to the scene, but a PECO official tells Action News they have not yet responded.