BERTHOUD, Colo. (AP) _ A fast-growing wildfire whipped by 50-mph wind gusts threatened dozens of homes as it burned through 600 acres of grass, brush and timber Wednesday night.

About 70 firefighters were at the blaze about 40 miles northwest of Denver.

``You couldn't see anything. Even when it was light, it was black,'' said Robin Smith, who fled his house west of Berthoud.

Smith and his wife, Anne Marie, grabbed insurance papers and a few valuables and drove down the steep, winding dirt road to Berthoud, about 10 miles away. They brought one of their cats but couldn't find two others.

Fifteen to 20 houses were evacuated, said Erik Nilsson of Larimer County Emergency Management. There were no immediate reports of injuries.

The cause of the fire had not been determined.