One man was killed and at least six people were injured by a storm -- unofficially dubbed a tornado -- that ripped through the county at about 7:45 p.m. Sunday.

Damage was centered in the Clark area.

Charles E. Templeton, 81, of 22 Milton St., Clark, was killed when his house was leveled by the storm, said Mercer County Coroner J. Bradley McGonigle III. His wife was also in the house at the time and was one of the injured taken to a local hospital, said Jefferson-Clark Regional Police Chief Jeff Lockard.

The hospital of Sharon Regional Health System treated four people, admitting a an 85-year-old woman -- she was in fair condition -- and sending a 52-year-old man to St. Elizabeth Health Center, Youngstown, a spokesman said.

The hospital also treated a married couple.

UPMC Horizon, Farrell, admitted a woman in stable condition, and UPMC in Greenville treated a man, spokespeople said. Names of the injured were unavailable.

The hardest hit area in Clark was Milton and Nora streets, Lockard said. About four houses were completely destroyed and there was a major gas leak in the area, but it was contained, Lockard said.

Rescuers were canvassing the area into the night looking for victims. Clark Fire Chief Gregg Sanford said rescuers were using a thermal imaging camera to search all homes for the second time.

Jason Wagner, who lives in an apartment building on state Route 258, said he was outside smoking a cigar when he saw the storm coming.

"I saw the lightning flashing ... I noticed the clouds were peaking down," he said. "From watching the movie 'Twister' I knew a tornado was starting to form. Then there was a tornado. I said, here it comes."

"We all ran into the bathroom," said another resident of the building, Tasha Matijevic. Although the roof was ripped off the apartment, no one was injured.

Although many witnesses said they saw a tornado, Mercer County Emergency Management Director Jim Thompson said it was "way too soon to tell what kind of weather event this is."

Meteorologist Terry Parrish, of the National Weather Service in Pittsburgh, said a survey team probably would be sent to the area today to try to determine what type of storm struck.

The storm was caused by cold air from Canada clashing with the warm air that had brought Indian Summer to the area the last couple of days, Parrish said.

Rain, hail and high winds were reported through eastern Ohio and western Pennsylvania, he said.

"It sounded like the authentic freight train coming by," said John Bush of Clark, whose house was hit. "We heard it coming and we made it to the basement just in time."

Trees were ripped like they'd been hit by artillery shells, while others were uprooted. The pungent aroma of pine filled the air.

Bush's tractor-trailer was moved around like it was a Matchbox truck. Siding was peeled off homes.

Valley View Road in South Pymatuning Township was blocked by a large tree. Many other trees were also down. Power lines were down and utility poles were snapped off at their bases like pencils.

Debbie Small, a Valley View Road resident, was out with her flashlight to see if her neighbors were OK. She said a magnolia tree in her backyard had been uprooted, and an oak tree was just about gone.

"I heard the wind come up," she said. "I just barely made it into the cellar."

A staging area manned by fire, police and ambulance personnel, 911 officials and medical personnel from SRHS and UPMC was set up at Tara -- A Country Inn in Clark.

Residents not permitted to return to their damaged homes were offered temporary shelter at Tara, the Radisson Hotel in Shenango Township and at Reynolds Junior-Senior High School, where the Mercer County Red Cross had set up cots for 80 people. Officials expected 40 to 50 people.

The hospitals triggered their disaster plans.

While no injuries were reported from the Shenango Valley, emergency crews worked much of the night moping up from storm-related damage.

In Sharon, the roof of the Standard Market, 588 New Castle Ave., was ripped off, and a nearby house on Budd Street was damaged.

Sharon firefighters reported wires and trees down and street lights out throughout the city.

Farrell firefighters guided motorists around downed wires as they waited for Pennsylvania Power crews to arrive to disconnect them.

Farrell fire Chief Joseph Santell said trees and wires were down all over town, and street crew members and firefighters were clearing streets as best as they could. A tree caught fire on Fruit Avenue.

Santell said there probably was some home damage from falling debris, but he heard of nothing that was serious.

Penn Power reported 4,600 customers without power in Mercer County, the bulk in the Clark area, and another 600 in Trumbull County.

The Rev. Jeannette Wright-Hooks was driving in Farrell when the storm hit.

"It was so dark, and the rain," said the Farrell councilwoman. "It reminded me of 'The Wizard of Oz.' All you could do is creep and pray because you couldn't see anything."

Rev. Wright-Hooks said had to drive on sidewalks to get around a tree down in the 1200 block of Roemer Boulevard.

Outages can be reported to Penn Power at 88-LIGHTS or (800) 720-3600.

Herald Staff Writers Kristen Garrett and Larissa Theodore contributed to this story.