Two people have died and multiple others are injured after an explosion caused a nursing home to partially collapse in the US state of Pennsylvania.

Emergency crews were called to the Silver Lake Nursing Home in Bristol at about 14:00 local time (19:00GMT) on Tuesday after receiving reports of a gas odour. When crews arrived, the building exploded causing a massive fire, authorities said.

Five people are still unaccounted for, but authorities said they are unsure if those people are in the building. Others have been rescued

Governor Josh Shapiro said the exact number of injuries is not yet known, and the cause of the blast is under investigation.

In the chaos of the explosion and fire, emergency crews pulled residents out of windows, stairwells, and elevators and carried them to safety, fire chief Kevin Dippolito said.

“There was one police officer who literally threw two people over his shoulders and ran” with them toward medical staff, he said.

Several people were trapped in the basement of the collapsed building and rescued, Dippolito said.

Responders on Tuesday evening were still searching the building for potential rescues, Dippolito said.

Images and videos posted on social platforms by local media outlets show a partially collapsed building with massive flames billowing out of it.

Shapiro commended the support from authorities around the region who rushed to offer their help, and added that the residents living near the nursing home were “outstanding”.

“We had residents coming out of their houses offering to help us,” he said. “This is the Pennsylvania way: neighbors helping neighbors in a moment of need.”

Shapiro offered his prayers “for this community, for those who are still missing, for those who are injured, and for those families who are about to celebrate Christmas with an empty chair at their table”.