Authorities were investigating a disturbance of some sort, which initially was reported as a manhole explosion, near 30th and Market Streets in University City on Saturday afternoon.

No one was injured, a police spokeswoman said.

The reported underground explosion occurred near 30th Street Station, at the northeast corner of 30th and Market, shortly after 1 p.m., a Fire Department dispatcher said.

Market Street was closed to vehicular traffic from 29th to 30th Streets because of the investigation.

It was unclear what had happened. There was no sign of fire, and authorities could not confirm whether something exploded.

"We didn't have any gas readings, so it wasn't gas," said PGW spokeswoman Janis Shields, who said PGW staff were called to assist. But with no gas leak or other issue found, she said, they had no further involvement.

"This is completely not a Peco issue," said Debra Yemenijian, a spokeswoman for Peco Energy Co. She said there was no Peco equipment in the manhole, which she noted was abandoned. No Peco customers were affected by what happened, she said.

"It's not us," said Amtrak spokesman Craig Schulz. Contrary to some initial reports, he said, 30th Street Station was never evacuated or lost power, and Amtrak service was completely unaffected by whatever had occurred.

"Definitely not SEPTA," said Carla Showell-Lee, spokeswoman for the transit agency. She said the incident disrupted some Regional Rail service and the Market-Frankford Line for about half an hour, and buses were detoured for several hours.

All were back to normal Saturday night.

jlai@phillynews.com

856-779-3220 @elaijuh