HOLT, Mo. -- The parents of a teenage girl who disappeared along with her boyfriend made a plea for her to contact them on Tuesday.

Authorities were looking for Levi Carlson, 16, and Christina Paige Alley, 14.

An Amber Alert was issued for the pair in Missouri.

"Please, please find a phone. Get on the Internet, whatever you can do. Please just get a message to us somehow. Call one of your friends," said Alley's father, Jeff Alley.

Carlson and Alley, who are dating, left at halftime of a high school football game Friday night in Lathrop, Mo., and haven't been seen since.

Investigators don't know whether Carlson took Alley or if she left with him willingly, they said.

The two were believed to be in a maroon 1996 Toyota Avalon with four doors and Missouri license plate PD0 A5U.

Neither of the teenagers have a license. They had a little bit of cash, but not much, and there hasn't been any activity by them on any credit cards.

Alley's parents hope she and Carlson are still in the Holt area. They've been out driving around looking for the teens. It's deer season, so her parents said they hoped some hunters might locate the pair.

To Carlson, Jeff Alley said, "We've known you since you were little, and we've always treated you with respect and kindness, and we're worried about you too."

No one witnessed any incidents between the two before they disappeared, but authorities are concerned because Carlson has a medical condition, is prone to violence and not taking his medication, said Maj. John Farmer, of the Sheriff's Department.

He'd had an argument with his parents on Wednesday.

"We're always worried when teenagers take off like that. There's no communication from Friday to today, so every day that goes by, to us, it just gets worse and worse," Farmer said.

Christina Alley is white with brown hair and blue eyes. She's about 5 feet 2 inches tall and weighs about 130 pounds. She has a round birthmark on her hip and was last seen wearing a blue shirt, black pants and sandals.

Carlson is a white male with brown hair and brown eyes. He weighs about 225 pounds.

The Sheriff's Department urges anyone who saw the vehicle or had any information about their whereabouts to call 911 or the Sheriff's Department at 816-539-2156.