A pair of masked men who were robbing a Pennsylvania convenience store Monday were shot and killed by a customer, authorities said.

The unidentified patron was arrested after allegedly gunning down two men who had held up Krick's Korner in Reading, Penn., just after 2 p.m. Monday, Police Sgt. John Solecki told the Associated Press.

The customer is believed to have fired his weapon after entering the store and spotting the masked men. After he shot the alleged thieves, one ran but fell roughly 20 feet from the store, while the second fell in a nearby crosswalk, according to the Reading Eagle.

The robbers allegedly had stolen cigarettes, lottery tickets and some cash from the store on Ninth and Exeter Street, the Reading Eagle reported.

The alleged gunman was arrested, investigators said, adding that a police investigation was underway.

The Associated Press contributed to this report.