A total of three teenagers have now been arrested and charged in connection with the brazen armed robbery of a Vancouver jewelry store last month, but police believe the masterminds behind the heist are still at large.

Investigators say a suspect entered Montecristo Jewellers, located in the Oakridge Centre mall, on Sept. 30 posing as a customer and speaking with store staff before pulling out a firearm.

Two other suspects approached the store, attacking a security guard, firing gunshots and discharging pepper spray outside.

Police arrested one suspect -- a 16-year-old boy from Surrey -- after he allegedly fired another shot outside the mall. Two others made their way to a red van and were driven away by a fourth suspect.

This week, police arrested an additional two Vancouver teens, aged 16 and 17, in connection with the robbery.

The three youths have been charged with numerous firearms, assault and robbery-related offences. The store's security guard sustained minor injuries in the robbery, as did a female employee who was struck on the head.

But investigators do not believe that the teens were responsible for the planning of the robbery, and continue to search for more suspects.

"Make no mistake, getting involved in something like this for the promise of compensation or other reward is at the least foolhardy, but at the most, could result in deadly consequences for those involved," Sgt. Dale Weidman said in a release.

"It isn't the masterminds behind it that will take the fall -- they'll just move on and find someone else to do their dirty work while others sit in jail."

The same jewelry store was also targeted during a November 2007 heist, in which two men attempted to steal tens of thousands of dollars worth of Rolex watches. Both were caught within a week.

The downtown Montecristo Jewellers location was also robbed at gunpoint in May 2009.