TUPPER LAKE -- A downstate man was seriously burned during an apparent explosion at a local camp Sunday evening.

State Police said Andrew C. Schillinger, 58, of Nassau was spending the holiday weekend at a hunting camp on the Pitchfork Pond Road when a sudden blast sent flames surging through the one-story residence.

Officials said it appeared he was the only person at the camp when it was rocked by the explosion around 6 p.m.

It was unclear Monday whether the Rensselaer County man was inside or outside of the camp during the blast, but Ray Brook-based investigators said he suffered third-degree burns to more than 80 percent of his body.

Tupper Lake First Assistant Fire Chief Mark Picerno said a neighbor heard the explosion and found Schillinger badly burned.

Picerno said that after calling 911 the neighbor helped get the injured camper into a vehicle and drove him toward Adirondack Medical Center until members of the Tupper Lake Rescue Squad could intercept them.

Schillinger was later taken to Fletcher Allen Health Care in Burlington, where he was listed in critical condition Monday evening.

Franklin County Emergency Services Deputy Director Ricky Provost said Tupper Lake firefighters were at the seasonal camp for several hours Sunday night dousing the flames and trying to determine how the fire erupted.

Picerno said "the whole building was engulfed by flames" when crews arrived.

Fire officials and members of the Franklin County Cause and Origin Team returned to the charred camp for several hours Monday but were unable to determine the exact cause of the blast.

"We know that there was an explosion, but we don't know how the explosion happened," the assistant chief said Monday afternoon.

He said it was still unclear whether the blast occurred inside or outside of the camp.

State Police officials said it appeared to be accidental.

Officials were unclear whether Schillinger owned the camp, which was destroyed by the explosion.

avanvalkenburg@pressrepublican.com