BOZEMAN (AP) -- A storm packing 85 mph winds and producing golf ball-sized hail moved through southwestern Montana on Tuesday afternoon, downing trees and knocking out power to several thousand residents.

Dan Zumpfe, a meteorologist for the National Weather Service in Great Falls, said the storm formed southwest of Dillon and moved toward the Bozeman area. He said wind gusts as high as 85 mph were reported in Ennis, and windows were blown out in Sheridan.

''We got numerous reports of penny-sized to golf ball-sized hail,'' said Zumpfe, who could not confirm the touchdown of a tornado. ''There may be a whole bunch more damage that we're unaware of at this time.''

Steve DiGiovanna, deputy disaster emergency services coordinator for Madison County, said no injuries or deaths had been reported in the county, but a roof was ripped off in Ennis and several trees and power lines were down.

''We had 2 1/2 hours of high activity here,'' he said. ''It was loud, it was noisy and it was pretty ominous for a while.''

The storm brought down power lines as it tracked northeast, and electricity was knocked out at two substations near Bozeman, said Claudia Rapkoch, a spokeswoman for NorthWestern Energy.

''We have had several thousand customers affected by this storm,'' she said.