An explosion tore through a church in upstate New York on Tuesday, injuring five people, including a firefighter who suffered severe burns while responding to reports of a gas smell inside the building, officials said.

New York State Police were investigating the cause of the blast, which occurred around 10:30 a.m. at the Abundant Life Fellowship Church in a rural area about 50 miles (80 kilometers) northeast of Syracuse.

Five people were taken to a local hospital for treatment. Two were listed in critical condition, including a firefighter who responded to the scene. The remaining three people were being treated for injuries that were not believed to be life-threatening, police said.

Police said there was no initial indication of criminal activity related to the explosion, which sent thick plumes of black smoke into the air and severely damaged the church.

The church was reportedly heated by propane cylinders, according to state troopers.