After a massive explosion rocked a South Philadelphia block on Thursday, Philadelphia firefighters threw their ladder onto a pile of rubble and dove into the blaze in an attempt to save a person trapped beneath a pile of debris.

The firefighters weren’t successful. But dramatic video taken in the moments after the blast shows a half-dozen first responders inside a fiery inferno, attempting to pull the person from the rubble. Just after the video ends, a second house collapsed. Fire Commissioner Adam Thiel said it was a “punch in the gut” for first responders.

“Bravery in action,” said Mike Bresnan, president of the International Association of Fire Fighters and Paramedics Local 22, who provided the video to the Inquirer.

Officials haven’t yet determined a cause for the explosion on the 1400 block of South Eighth Street that left at least two people presumed dead. Crews controlled the massive blaze in about three hours Thursday, but concerns about the stability of the buildings and street were delaying recovery and excavation efforts.