Nicholas "Cole" Balderson, 17, was last seen at his Brookeville residence on Jan. 12. Balderson's girlfriend, Rachel Elizabeth Reilly, 16, of Olney, was last seen in his company on the same day, according to the Montgomery County Police Department in Maryland.
The teens were reported missing after failing to check in with family members.
Authorities believe Balderson and Reilly left the area in his 1989 Jeep Wrangler. Over the weekend, officers with the Virginia State Police found the vehicle abandoned at a rest area on Route 81, about 100 miles north of Roanoke.
"Police and their families are concerned for their welfare due to their ages and the length of time that they have not been in contact with family members," Montgomery County Police said.
Both teens' phones have been turned off since the day they went missing, and there has been no activity on any of their online accounts. Interviews with their friends and family members -- who have described their disappearance as out of character -- have not resulted in any useful information regarding the teens' whereabouts, police said.
"It was not planned, they did not take anything with them, they don't have any money," Reilly's mother, Karen Reilly, told Washington's WUSA-9 News.
Montgomery County Police Cpl. Dan Friz said it is unusual for runaway teens to be gone for such a long period of time without reaching out to someone, according to WUSA-9. He also said there is always a risk that they could come into contact with a predator.
Balderson is described as a white male, 5 feet, 10 inches tall, 140 pounds, with green eyes and shoulder-length brown hair. A clothing description is not available. Reilly is described as a white female, 5 feet, 5 inches tall, 125 pounds, with hazel eyes and long brown hair. Her clothing description is also unknown.
Anyone with information in the case is asked to contact the Montgomery County Police Family Crimes Division at 240-773-5400 or the America's Most Wanted tip line at 1-800-CRIME-TV. Concerned citizens have also created a Facebook page devoted to the teens' disappearance.