Honolulu police said there may be at least three different individuals or groups involved in fast-food restaurant, convenience store and bank robberies in the last few months.

Criminal Investigation Division Commander Maj. Lester Hite said the suspects generally are all  masked, wearing hoodies or caps, many are armed with rifles or handguns and are careful to leave no fingerprints.

Police held a news conference Friday at the main police station where they also offered safety tips for businesses, customers, employees and the public, and urged the public to call 911 and not to approach a possible suspects since they may be armed and dangerous.

At least 11 armed robberies have occurred within the past month at convenience stores, 24-hour drug stores and fast-food restaurants from June 30 to Friday.