A woman eating her lunch while sitting in her car under a shady tree in a church parking lot was carjacked at knifepoint Wednesday.

About 12:45 p.m., a 32-year-old woman was in her car near 5900 S. Highland Drive when she was approached by a man on a mountain bike, said Salt Lake County Sheriff's Lt. Paul Jaroscak.

"He asked her for a ride. She agreed," he said.

While the man put his bike behind a storage container, the woman cleared some items off the passenger seat. But when the man approached her again, he pulled out a pocket knife with a three-inch blade and demanded she get out of the car, Jaroscak said.

The man took off in the woman's vehicle and was last seen driving north on Highland. As of Wednesday afternoon, investigators still were searching for the car.

Although she lost her vehicle, sheriff's Capt. Chris Bertram said it was fortunate she wasn't hurt.

"This is a very dangerous situation. She's very lucky. Sometimes they don't let the girl get out," he said."We want to believe people are good and be good-natured, but it's not a safe situation. We just don't know what's going to happen (when we offer rides to strangers)."

Investigators were looking Wednesday for a white man in his 20s about 5-foot-10 and 150 pounds. The woman's vehicle is a silver 2003 Chevy Impala with Utah license plate number 604 NCS.