Police are investigating whether the armed robbery of a Brinks truck on Tuesday outside a Philadelphia-area store is related to four other attacks on armored vehicles in and around the city this summer.

One of the suspects is a former Brinks employee who had recently been fired. The robbery was one of five similar crimes in the area in less than two months.

Two suspects, armed with an AR-15 style pistol and a handgun, approached the armored truck’s driver, forced her to hand over her gun, and stole between $700,000 and $800,000, Cheltenham Police Lt. Andrew Snyder told CBS News.