Updated

A tornado ripped a family's farmhouse from its foundation in Montana's remote northeastern corner, killing two people and leaving neighbors and authorities to dig through the rubble to rescue a 71-year-old woman who was found next to her grandson's body. Her nephew was found dead 200 feet away.

Robert "Robby" Richardson, 10, and Steven D. Smith, 46, died of blunt-force head and chest injuries at the farm 13 miles west of Reserve on Monday night, Sheridan County Coroner David Fulkerson said.

Barbara Smith, 71, was taken from the basement of her home to a hospital in Plentywood and was later transported to the Billings Clinic, where she was listed in serious condition Tuesday evening, hospital spokeswoman Julie Burton said.

The tornado that touched down west of Reserve about 7:15 p.m. Monday was reportedly two to three miles wide with winds estimated at 150 mph, National Weather Service spokesman Brad Mickelson said.

That wind speed put the tornado's rating at EF3 on the Enhanced Fujita Scale, making it only the fourth tornado in Montana's history powerful enough to achieve that rating, Mickelson said. It's the deadliest tornado to hit the state since 1923, he added.

Medicine Lake resident Brandon French said he and five other men watched the tornado from a hillside.

"It was a damn big one. It was a long way away, but you could see it clear as day," French said. "It was like nothing we've ever seen before."

French said they got a call from the owner of a bar in Reserve who had heard that a farm to the west had been hit. The men got into a pickup truck and were among the first to arrive.

The two-story house, barn, lean-to and various buildings were simply gone, he said.

"There's no houses, there's no buildings, there's nothing left," French said. "The vehicles were all turned over, there was a pickup plowed into a tractor — it just wrapped the pickup around the tractor. You couldn't peel it off."

Sheridan County Sheriff Patrick Ulrickson said the damage was devastating — the house was completely gone from the foundation. The tornado also destroyed all the other buildings on the property, he said.

"We had a Quonset hut that was crushed like a pop can," he said.

Todd McCabe also headed to the farmhouse after receiving a call from the bar owner in Reserve. He said he arrived as five or six neighbors were trying to reach the basement.

With the house gone, the basement was just a hole in the ground covered with debris, he said Tuesday. The neighbors dug through rubble and found the elderly woman.

Barbara Smith was conscious, but the boy next to her was still, he said.

"The lady was trapped down there, and we just tried to get the stuff off from on top of her," McCabe said. "The boy was found right next to her. He was gone. The chimney fell on him and killed him."

Steven Smith lived in a trailer home on the property, which was also destroyed, Fulkerson said. Smith may have been trying to reach the basement when the tornado struck, though it was impossible to know for sure, he said.

A county bridge also was destroyed, along with at least nine grain bins and an uninhabited farm house, and about 20 cows were killed or seriously injured, according to an assessment by county, state and weather service officials.

Electricity was restored to all but a few customers in the area, county commissioners said. About 25 lineman and contractors were helping rebuild six miles of downed power lines, said Sheridan Electric Cooperative purchasing agent Scott Powell.

Montana has about seven tornadoes a year, according to the National Climatic Data Center. A June 20 twister tore apart the state's largest indoor arena and was the first large tornado to hit Billings in more than a half-century.