PHILADELPHIA (CBS) — Fire crews have recovered one body as the recovery and investigation phases continue after three row houses were leveled by an explosion and fire in South Philadelphia. Fire Commissioner Adam Thiel says a second person remains missing and is presumed dead.

Fire crews worked through the night to extinguish the fire that sparked around 11:30 a.m. Thursday on the 1400 block of South 8th Street.

Thiel says this is a delicate and dangerous process as they begin searching for victims. Three homes collapsed and two more were severely damaged and are in danger of collapse.

When fire crews arrived on the scene Thursday, they spotted one person in the rubble. However, because of the growing fire and a second collapse, Thiel said crews were unable to rescue the person.

During the fire fight, another person was reported missing by family members. That person is believed to be in an adjacent house.

“We live and regrettably sometimes die to make rescues and it’s tough for us when we can’t,” Thiel said.

Officials still haven’t said what caused the explosion, but people in the neighborhood reported smelling gas.

The Philadelphia Fire Department says gas and power to part of the neighborhood will be shut off intermittently as the investigation continues.

Sixty people were displaced and at least a dozen homes were damaged by debris. Thiel is asking for patience from the neighborhood.

“If you live in that block, there’s still going to be some uncertainty about when you can go home, whether you can go home, what you’re going to find when you go home,” the fire commissioner said.

Thiel also applauded the heroic acts of many neighbors on the block who jumped into action.

“As we learn more and more about all the things that were happening beyond the incident, we really saw the best of Philadelphia yesterday in the wake of this tragic event. We had neighbors helping neighbors, friends helping friends, families helping families, and a lot of folks who actually risked their lives to try to rescue complete strangers,” Thiel said.

The incident has crippled the neighborhood.

“It’s insane,” said Vincent Termini Jr., the owner of Termini Brothers Bakery. “Streets are closed, our trucks have a hard time getting out. You’re just trying to get through it.”

A major obstacle that crews are dealing with is that a sinkhole may be forming in the road so they cannot bring in heavy equipment until it’s secured.

A timeline has not been given on when people on the block will be allowed back home.

CBS3’s Howard Monroe contributed to this report.