Excerpts from abc7chicago.com:

Investigators said a gasoline leak into the water supply was the cause of a large explosion and fire at a condo building in south suburban Willowbrook.

Firefighters from at least 10 departments responded to the Knolls Condominium complex in the 6100-block of Knoll Wood Road Friday morning.

Tri-State Fire Protection District officials believe the gasoline leak originated at a Speedway gas station in neighboring Westmont. There is still gasoline running through sewers from Westmont to the water reclamation plant eight miles east.

Officials are continuing to flush out the water system and are also trying to open the sewers so the gasoline fumes can escape. Fire officials said there have been 10 explosions as a result of the gasoline leak, and no serious injuries have been reported.

A resident pulled a woman out of the building as Willowbrook police and firefighters arrived. She was taken to Loyola Hospital for treatment and is expected to be okay. No other injuries were reported.

“What the fire department has determined either gasoline or some other flammable chemical had been introduced to into the sanitary system,” said Willowbrook Fire Chief Robert Pavelchik.

The Environmental Protection Agency and sanitation district were notified. Anyone who lives in the area and notices the smell of gasoline should open their windows and doors, turn off all ignition sources, and call 911. Fire officials said people are allowed to use their appliances.

At the condo building, all ignition sources – both electric and gas – were immediately turned off and residents were evacuated from their homes. But the calls for help actually started Thursday night, when residents reported smelling gas.

“We had to sleep in our front room because in our room, in the master bedroom where me and my girlfriend sleep, the bathroom smelled like gas. I smelled gas all through our bathroom,” said resident Christopher Simmons.

“They couldn’t find the source and here we are again this morning, in the same neighborhood,” Pavelchik said.

“I believe they could have did more than what they did last night. All they did was come here and turned off the alarm and left,” Simmons said.

The American Red Cross was contacted to provide aid to those who have been evacuated. They will not be allowed to return until investigators determine the source of the explosion and correct the problem.

Firefighters responded to a separate fire early Friday afternoon in the 300-block of 63rd Street. They were able to rescue a dog from the smoky blaze and no one was hurt.

thanks Scott