Witnesses say a deadly tornado obliterated a farm in Montana last night -- wiping away a house, barn and other buildings. Two people were killed and a third seriously injured.

A group of men who'd been watching the twister from a hill were among the first people to arrive at the scene. They say all that was left of the house was a hole in the ground filled with debris -- so they they started digging through it. They found an injured 71-year-old woman next to the body of her 10-year-old grandson. Her 46-year-old nephew was found dead 200 feet away.

The woman is listed in serious condition in a Billings hospital.

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