Officials have revealed the cause of a strange odor that forced over 100 people out of their homes in Montgomery County, Pennsylvania.

Officials say gasoline got into the sump pumps of three of the homes at the Fairlawn Court development in Skippack Township. The gas flowed into the pumps through runoff water, according to investigators.

Neighbors along North Gorski Lane off Route 113 first evacuated their homes voluntarily after noticing the odor from the gas around 7 p.m. on Sunday.



"Something don't smell right," said Fairlawn Court resident Matt Loughan after his wife called the strange odor to his attention.

Responding officials at first believed the odor was that of hydrogen cyanide, a bi-product of fires that can be deadly in high concentrations.

"As soon as I walked in, my meter went into alarm and in each unit we kept getting readings," Skippack Fire Chief Haydn Marriott said of the mystery chemical compound.

Residents were asked to open their windows and stand outside their homes. According to the Montgomery County Emergency Response team, over 100 people were evacuated but only residents who had a gas leak reading were told they had to stay out.



Samples of the compound were taken to the Environmental Protection Agency. Monday afternoon, officials determined that it was gasoline. They have not yet determined the source of the gas however.

Despite the bad smell, officials say the gasoline odor did not pose a health risk to any of the residents.

Skippack Fire Chief Haydn Marriot made the announcement that displaced residents were allowed to return home after their home was metered.



"We're checking each house individually and if the meter reads zero, residents are free to go back in," said Marriot.

Officials tested 171 homes and gave 161 of the houses the all-clear. The remaining ten homeowners are people who they have not yet gotten in touch with.

Officials with the Red Cross assisted the displaced residents on Sunday, providing food, drinks and shelter for four of the families. They left on Monday after the evacuated homes were determined to be safe.

Contact Sarah Glover at 610-668-5580, sarah.glover@nbcuni.com or follow @skyphoto on Twitter.