Grizzly bear killed after "surprise" attack on father and son in Montana

A grizzly bear seriously injured a father and son who were hunting in northern Montana in a "surprise" attack, wildlife officials said. The bear charged out of a thickly wooded area and attacked the two on a road Saturday near Smith Lake north of Whitefish Lake in the Flathead Valley, according to the Montana Fish, Wildlife & Parks state agency.

The hunters "sustained significant injuries" before they shot and killed the bear, the agency said in a statement. They were later flown to a hospital.

Investigators found a deer carcass nearby. They concluded the nearly 20-year-old female was defending the food and her cubs.

"Based on the evidence gathered at the scene and interviews with the victims, we believe this was a surprise encounter involving an adult female grizzly bear defending a food source and her offspring," FWP Regional Game Warden Captain Lee Anderson said.

Bear attacks on humans are rare, but the animals are increasingly active in the fall months before denning season, the agency said, the agency said. Bears typically enter their dens for the winter beginning in late November.

Montana's grizzly and human populations have both risen substantially since 1975, when the bears were protected under the Endangered Species Act, "60 Minutes" correspondent Bill Whitaker reported last month. See his full report below.