Temperatures may have warmed up slightly Friday, but the winter woes continued to hit some Minnesotans hard.

At least 50 vehicles were involved in a pileup that briefly closed the northbound lanes of I-35 in Lakeville on Friday afternoon.

Snowy and icy roads may have led to the initial crash on the road near the County Road 50 bridge, which led to a number of subsequent crashes involving semitrailer trucks and vehicles, as well as a traffic backup for at least 5 miles to the south. There were no serious injuries.

"It was kind of a snowball effect," said State Patrol Lt. Eric Roeske.

The first crash occurred shortly before 1 p.m. The Minnesota Department of Transportation called upon numerous towing companies that worked furiously and had the interstate reopened shortly before 3 p.m.

At least six semitrailer trucks slid into the ditch or off to the side of the road, Roeske said.

State Patrol Lt. Steve Hanson said whiteout conditions, either from the falling snow or from snow being kicked up by large trucks, blinded drivers who crashed into cars that had stopped or crashed in front of them. Some drivers slid into the ditch. Even after crews were on the scene, cars kept sliding off the road.

Another crash scene unfolding about 2 p.m. had traffic slowing down briefly on southbound I-35W at the Crosstown in Minneapolis. Several squad cars responded to that incident. One vehicle was on its side up against a sound wall.

The treacherous midafternoon travel spread as far east as Menomonie, Wis., about 40 miles from the Twin Cities. Numerous crashes had the eastbound lanes closed, according to transportation officials in that state.

Meghan Holden is a University of Minnesota student reporter on assignment for the Star Tribune. Staff writers Tim Harlow and Paul Walsh contributed to this report.