A Whitby teenager faces charges after police say he helped rob the Tim Hortons where he worked.

A Tim Hortons was robbed in Whitby Sunday night after a masked male entered the store armed with a knife, and demanded money. After leaving the store with what police describe as "a small quantity of cash," the suspect got into a car parked nearby.

Police stopped the alleged getaway vehicle a few minutes later and arrested two male Whitby teenagers -- 18-year-old Thomas Dennis and a 17-year-old male who cannot be named because of his age. Both suspects face several charges, including assault with a weapon, robbery and possession of property obtained by crime.

Since then, an 18-year-old employee of the coffee shop has also been arrested, with police alleging that he gave the other two suspects information to help facilitate the robbery.

Brandon Mahar faces charges of robbery and conspiracy to commit an indictable offence. He was also charged with possession of an illegal substance after allegedly being found with cocaine at the time of his arrest.

Mahar was arrested Friday and has been held for a bail hearing.

Anyone with information about the case is asked to contact investigators at 1-888-579-1520, ext. 5355. Anonymous tips can be sent in through Crime Stoppers at 1-800-222-8477, or online through www.durhamregionalcrimestoppers.ca.