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.

Three men were arrested for stealing more than $2 million from a Brinks truck outside a Home Depot in Philadelphia in June.

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.