Fire officials said two Philadelphia Gas Works employees were in the basement of a row home along 18th and Bancroft streets near Mifflin when the gas explosion happened around 7:00 p.m. Thursday.
The two PGW employees and a resident were injured in the explosion. They were taken to the Hospital of the University of Pennsylvania with non-life-threatening injuries.
93-year-old resident Antoinette Marchand was at home with her dog when suddenly she heard an explosion.
"The dog jumped. I grabbed hold of the dog. I called 911 for the fire department," Marchand said.
The explosion was so powerful, it knocked down book cases and other items in nearby homes.
"In our backroom, a lot of the stuff had fallen down. So I went to the back, went out to the yard, all bricks, can't even get out there," neighbor Joe Delullo said.
Fire officials say it appears something went wrong with the furnace in a row home. The subsequent fire spread to two adjacent homes.
"Never happened in all my 93 years, never experienced anything like this in my life," Marchand said.
The Red Cross says at least 3 families have been displaced.
One family spent the night at a Red Cross shelter and other evacuees are staying with family or friends.
PGW crews worked through the night to make repairs.
The Associated Press contributed to this report.