(Newser) – Over a period of three hours Saturday, five US Postal Service mail carriers were shot with paintballs in what police are calling a series of attacks carried out by two men. The USPS' law enforcement division is offering a $50,000 reward for information leading to the paintball gunmen, Fox 5 DC reports. The afternoon attacks carried out in Washington, DC, and Maryland's Prince George's County left several of the USPS carriers with minor injuries, WTOP reports. (Read more paintball stories.)