A possible gas explosion left several rowhomes in Allentown engulfed in flames overnight. At least 10 homes caught on fire, officials say.

It happened on the 700 block of North Fountain Street, around 3:15 a.m. Sunday.

UGI Utilities says it appears there was an explosion that led to a three-alarm fire. However, it remains unclear what sparked the explosion

The incident caused at least one home to collapse, Allentown Fire Deputy Chief Efrain Agosto said during a press conference Sunday morning.

“When the guys got here, they found one structure pretty much completely collapsed with fire in place,” Agosto said.