Aug. 12 (UPI) — One person was killed, three were hospitalized and several others remained missing Saturday in the wake of an explosion that destroyed or damaged at least a dozen homes near Pittsburgh, officials said.

The blast in the borough of Plum, located about 15 miles east of Pittsburgh, completely destroyed three homes and damaged at least 12 others, Allegheny County officials confirmed.

No cause was immediately identified.

The blast was reported at around 10:23 a.m., and when first responders arrived on the scene they reported there were people trapped under debris.

It appeared as if one house had exploded and two others were engulfed in fire while multiple other homes were damaged with windows blown out, officials said.

As of late Saturday afternoon, crews were continuing to search through the debris. The Red Cross and Salvation Army are assisting residents impacted by the explosion and the county announced it has set up disaster distress helpline and a shelter at a fire station in Renton, Pa.

Plum Mayor Harry Schlegel told WTAE-TV that one of the destroyed homes belonged to a borough manager, while James Sims, emergency management coordinator for Plum. said the damage was the worst he’d ever seen in the suburban community.

“I’ve been to six house explosions in Plum, and this is the worst I’ve seen in 47 years or 48 years, the worst one, just the amount of damage,” he told the station.

At least 18 fire departments have been assisting recovery efforts.