WESTBURY, N.Y. (CBSNewYork) — Nassau County police are on the hunt for a masked, knife-wielding suspect now connected to 15 armed robberies at local convenience stores.

According to police, the suspect was active on Wednesday night, hitting a 7-Eleven in Westbury — the second of two robberies connected to the string this week.

“Obviously now that I know that this store was hit, I have to be more aware,” one 7-Eleven customer told WCBS 880’s Mike Xirinachs. 

Earlier this week, a Dunkin’ Donuts on Powells Lane in Elmont was targeted, with the suspect flashing a large kitchen knife at a clerk before leaving the store with cash.

Other incidents include an April robbery of a Dunkin’ Donuts in Massapequa Park and the robbery of a 7-Eleven store in Old Bethpage in March, police said.

According to police, the suspect typically strikes when there are no customers on premises, and will typically wait nearby the targeted location before robbing the store.

So far, no one has been injured in any of the robberies, police said. As 1010 WINS Darius Radzius reported, Nassau County authorities would like to stop him before that happens.

“Thank God he has not hurt anyone, but we feel that he is getting more brazen as time goes on, and we want to apprehend him before somebody does get hurt,” Det. Lt. Richard LeBrun said.

Police have stepped up patrols and have increased the reward for any information leading to the arrest of the suspect to $10,000.

The suspect is believed to be between 25-30 years old and is described as being 6’0″ tall and around 170 pounds, police said. The suspect was last seen wearing a dark-colored hooded jacket, blue jeans and tan work boots, with a dark-colored scarf or bandanna over his face.

Nassau County Police is asking anyone with information to call Crime Stoppers at (800) 244-8477.