A Golden Valley police officer shot and killed an armed motorist Thursday, sending nearby drivers scurrying for safety, shutting down a heavily traveled highway and snarling traffic well into rush hour across the metro area.

Police said the officer had tried to stop the woman, who eventually pulled over along the median shortly after 1 p.m. Thursday on westbound Interstate 394 in Minnetonka.

"The lone occupant of the vehicle, an adult female, was in possession of a handgun and was subsequently fatally shot by the officer," according to a statement from Golden Valley police.

The unidentified officer, who was not hurt, was placed on temporary administrative leave, which is standard procedure.

The Hennepin County Sheriff's Office is investigating and declined Thursday night to release any additional details, including who the woman was, what led to the traffic stop and shooting, and whether she fired at the officer.

The shots could be heard at a nearby shopping area and transit station. Passersby stood on a grassy area along the highway and on the Hopkins Crossroad overpass to get an up-close look. After the shooting, some motorists were told to drive the wrong way on eastbound 394 to clear the scene. One man who was allowed through took video as he drove by.

Sidney Myers of St. Louis Park was pulling out of a parking lot near Dick's Sporting Goods when he said he heard three loud shots -- "pow, pow, pow."

"My first thought was, 'Wow, that sounded like gunfire,'" he said. When he drove on the frontage road along the south side of the freeway, he saw the white Honda Civic stopped on the south side of the freeway in front of a Golden Valley squad car. Within 30 seconds, Myers said, squad cars from "every possible department" converged on the area.

Courtney Pulsifer of St. Louis Park was traveling east to downtown Minneapolis. She slowed down when she saw the police officer on the westbound side standing behind his opened front door with his gun drawn. "It was crazy," she said.

Dozens of police cars blocked all lanes of I-394 as investigators arrived on the scene. Nothing was known about the woman, whose body could be seen lying between the median and her car, other than the Honda she was driving had California plates.

It was the second time in less than a month that a woman has been fatally shot by a law enforcement officer on a metro freeway.

On Sept. 3, state trooper David Kalinoff shot and killed Debra K. Doree, 48, of Landfall after he stopped her on eastbound Interstate 94 in Oakdale and she took off, dragging him about 200 feet. The trooper had been about to search the car, in which he had spotted "a crystalline white substance" that lab tests later found to be methamphetamine. A few days later, her husband, Scott Doree, and 21 others were charged with conspiracy to bring large amounts of marijuana and meth to the metro area.

On Thursday, Tony Shuster of St. Louis Park was headed east from the Ridgedale Center area when traffic slowed to a stop. He said other drivers were getting out of their vehicles to check out the cause of the delay when a passerby told him gunshots were involved.

"I thought 'C'mon, this is Minnetonka; that can't happen," said Shuster, who shot video of the scene with his iPhone. "It's not every day you see something like that in Minnetonka or anywhere really."

He said authorities directed drivers to turn around and head back west, going the wrong way to evacuate the area. He said that he and about 20 cars were so close to the scene that they were allowed to continue toward downtown Minneapolis.

The Minnesota Department of Transportation closed eastbound lanes but reopened them in time for rush hour. Westbound I-394, however, was closed from Hwy. 169 west to Hopkins Crossroad until it reopened about 7 p.m.

Jessica Brown was one of the motorists at a standstill as she left downtown Minneapolis to drive home to Plymouth. When she pulled over to see the scene with a crowd of onlookers, she said she was alarmed to hear that the congestion was the result of a fatal shooting on the busy road.

"This is a semi-busy road ... how many other people were on the road [when it happened]?" she said. "It shouldn't be happening over here. I mean, hello -- we're by Minnetonka."

Staff writer Matt McKinney contributed to this report. kelly.smith@startribune.com • 612-673-4141 pwalsh@startribune.com • 612-673-4482