A gas explosion sparked a fire in a South Philadelphia rowhouse Thursday night that displaced more than a dozen people, authorities said.

Philadelphia Gas Works crews were at the scene on the 1800 block of South Bancroft Street, working alongside firefighters and emergency medical technicians as neighbors watched from their windows.

The first fire call came in at 7:04 p.m., Fire Commissioner Lloyd Ayers said. A minute later, neighbors reported an explosion.

Responding firefighters saw light smoke coming from the top floor of a two-story house. Minutes later, firefighters reported heavy fire on the first floor.

At 7:19, the blaze was confirmed as a gas fire in the basement. Firefighters worked to prevent it from spreading as they waited for the gas to be shut off, Ayers said.

The fire spread into an adjacent house before being declared under control at 8:08, Ayers said.

Melanie McCottry, a PGW spokeswoman, said two workers for the utility suffered minor injuries in the blast.

She said the utility had been called to the scene at 5:30 p.m. to investigate a reported gas leak. Workers detected gas and started to turn off service to nearby houses, but could not gain access to two residences, McCottry said.

Four houses on the street remained without gas service Thursday night.

Ayers said 10 adults and three children were evacuated.

The Red Cross said it was assisting at least three families displaced by the blaze. The relief agency referred displaced residents to True Gospel Tabernacle Baptist Church at 16th and Mifflin Streets, where volunteers were providing aid.

Antoinette Marchand, 93, was in the kitchen of her Mifflin Street home when she suddenly smelled gas.

Her Chihuahua, Chi Chi, "looked at me, and her ears went back," Marchand said. Then she heard an explosion, she said.

She and daughter Denise DeLullo, 60, who lives next door, waited at the church for word on whether they could go back home Thursday night.