At least two people were presumed dead Thursday morning after a "violent" house explosion and subsequent fire rocked a number of homes in South Philadelphia, according to fire officials.

The explosion leveled three houses and significantly damaged two others around 11:36 a.m. at South 8th and South Franklin streets. Sixty people on the block were evacuated as nearly 120 firefighters battled the raging fires for hours.

"We believe now that we have pretty good confidence that there are two people who are missing and presumably deceased," Fire Commissioner Adam Theil said.

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Rescuers were still putting out "pockets of fire" in the burning homes, which were under control just before 3 p.m., Philadelphia's FOX 29 reported. Theil said the charred buildings were too structurally unstable "to put anyone else in there" as day turned to night.

Everyone in the affected homes was reportedly accounted for, but Theil didn't rule out the possibility that additional people may have been trapped in the rubble after walking by on the street when the explosion occurred.

"Don't know what's in the debris field," he said at a news conference Thursday night. “We’re not giving up. We don’t ever give up.”

Theil added that the "herculean" rescue efforts would start up again at first light Friday to remove the debris in the area and search for additional people who may be trapped underneath.

The explosion, described as "a firestorm," sent plumes of smoke that could be seen for miles, as wind gusts reached 20 miles an hour.

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"It sounded like a bomb exploded," one witness told Philadelphia's WPVI-TV.

A reception center at South Philadelphia High School was available for anyone affected by the fire. The Red Cross is also on the scene to provide aid as needed.

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Philadelphia Gas Works worked to shut off the gas in the area. Theil said a cause of the fire wasn't immediately known.