PHILADELPHIA (CBS) —Two SEPTA workers were injured while investigating a strange noise coming from a manhole Wednesday afternoon.

CBS 3’s Alexandria Hoff reports two SEPTA workers were called to investigate a strange noise coming from a manhole.

“They said it was possibly a leak and it smelled. I opened the door and I could just smell the gas outside,” one witness said.

SEPTA spokesperson Carla Showell-Lee says it happened at 49th and Windsor around noon.

“A fire erupted when they attempted to ventilate the manhole,” Showell-Lee said.

The workers were taken to Penn Presbyterian Medical Center.

(credit: cbs3)

(credit: cbs3)

Officials say one worker was treated and released with minor burns. The other was transferred to Temple Burn Center with first degree burns.

His injuries are non-life-threatening, authorities say.

Philadelphia Gas Works says the fire department will determine the cause of the fire and explosion once their investigation is complete.

PGW is keeping crews there to make sure that their infrastructure was not damaged during the fire.

No customers were affected.

The cause of the blaze is under investigation.