Firefighters battle a blaze that destroyed a home on the 2500 block of Mercer Butler Pike in Liberty Township, Mercer County, about 1 a.m. Thursday. A man who lived there was killed and his wife sustained burns in the fire that is under investigation by the state police fire marshal.

A 73-year-old man was killed and his wife was burned early Thursday morning when their house caught fire in Liberty Township, Mercer County, near the Butler County line, authorities said.

The 63-year-old woman was able to get her husband outside of the two-story home on the 2500 block of Mercer Butler Pike before he died, and she called 911 around 1 a.m.

Dispatchers advised emergency crews that the call was “an explosion with fire and injuries,” said Dan Hutchins, chief of the Springfield Township Volunteer Fire Department.

Investigators, however, were unable to immediately confirm there was an explosion.

The state police fire marshal is investigating the blaze, but a cause has not been determined. Fire officials have not ruled out smoking near an oxygen delivery device as a possible cause.

Both the husband and wife reportedly were smokers, authorities said.

Mercer County Coroner John Libonati pronounced Robert Vatter dead at the scene at 1:15 a.m. A cause and manner of death is pending the results of toxicology tests and forensic examinations. An autopsy was not planned.

“There is every indication (the cause of death) is going to be directly related to the exposure with the fire,” Libonati said. He also noted Vatter had “other significant medical conditions.”

Quality Ambulance and Slippery Rock EMS responded, and medics tended to Vatter's wife, whose name was not immediately released, before she was taken to Grove City Medical Center. From there, investigators said, she was to be transferred to UPMC Mercy hospital in Pittsburgh.

Authorities described her burns as “serious,” but she was conscious the entire time before being taken to the hospital. Her condition was not available.

“Based off of the general looks of the layout of the house,” Hutchins said, “I would say odds are (the fire) started in the (couple's) bedroom.”

He noted “there was oxygen present (an oxygen-delivery apparatus)” in the bedroom.

The home, which was heated by fuel oil, was engulfed in flames when fire crews arrived. Firefighters used a defensive attack and deployed a tanker shuttle.

There are no hydrants in the rural neighborhood, Hutchins said. Crews tapped a hydrant about three or four miles away near the Premium Outlets in the township as their water source for the tankers.

About 75 firefighters from 10 departments battled the blaze. None of the firefighters was injured.

The fire was under control in about 90 minutes, Hutchins said. During the fire fight, unknown family members of the couple showed up. Libonati said he spoke briefly to the couple's son at Grove City Medical Center, where the son had gone to be with his mother.

Trooper DuWayne Baird, a deputy fire marshal, was at the scene to begin his investigation of the cause and origin of the blaze. The state police crime unit at the Mercer barracks is also investigating.

“The chances of finding out a cause are going to depend upon further investigation, which is going to be interviews and a scene examination,” Baird said. “So, I'm probably going to have to come out in the daylight hours again and dig around.”

A key part of his investigation, he noted, would be an interview with the injured survivor.

Assisting the Springfield VFD were firefighters from Slippery Rock and Harrisville in Butler County; Pine Township, Grove City, Mercer East End and Jackson Center in Mercer County; Scott Township and Volant in Lawrence County; and Clintonville in Venango County.