Three teens are facing more than 70 charges in connection with a rash of thefts north of Toronto.

The robberies happened between March and May in Richmond Hill, police said in a statement Tuesday. More than a dozen commercial break-ins and 17 thefts from vehicles were reported during that period.

The teens are also believed to be involved in an early-morning daytime mugging on Monday.

Police say a man was walking in the area of Carville Road and Bathurst Street at approximately 1:20 a.m. Monday when he was approached by group of males. One of the muggers pointed a gun at the man's head while another person held a knife to his ribs, police allege.

Police say the man's backpack was stolen and the group of males fled the scene. The man was not injured during the incident.

Three 17-year-old males are facing more than 70 charges including robbery using a firearm, break-and-enter with intent and possession of property obtained by crime. The teens, who cannot be named under the Criminal Youth Justice Act, were scheduled to appear in court on Tuesday.

Police are still searching for a fourth person. They have not released a description of the suspect.

Police say they have recovered some of the stolen property, and investigators are asking anyone who may have been a victim to contact them.

York Regional Police's District Criminal Investigation Bureau can be reached at 1-866-876-5423, ext. 7241.