Flames engulfed a barn on a dairy farm in the southwest metro area early Tuesday, killing 13 cows and about 70 calves among the hundreds of animals kept on the property, authorities said.

Fire crews responded to a call from Halquist Farms on 182nd Street, west of Carver County Road 40, in San Francisco Township, said Belle Plaine Fire Chief Todd Otto. The farm is about 40 miles southwest of Minneapolis.

No farm employees or firefighters were hurt, Otto said. The cause of the blaze has yet to be determined.

"As of right now the speculation is electrical, but until we can get in there a little further and deeper we won't know," he said.

Investigators from the fire department, Carver County Sheriff's Office and state fire marshal's office are investigating, he said.

The fire was discovered as the farm workers went to milk the cows, the chief said. The dairy has about 400 to 500 cows, he said, but the fire was limited to the building used for calving.

The farm's owners are on vacation, Otto said, and are arranging flights home.

Two family members not on vacation were at the scene but did not return phone calls.

Star Tribune staff writer Tom Meersman contributed to this report. Paul Walsh • 612-673-4482