Playing around the train tracks is never a wise choice, but it’s an especially dangerous game when exploding tennis balls are involved.

And that’s what police say happened late last Friday night behind Thoreau Depot, where a group of youths scattered and left behind firecrackers debris and a tennis ball packed with match heads.

According to Concord Police Lt. Thomas Mulcahy, around 11 p.m. on Friday, July 27, an officer spotted a group of teens playing with fire works on the platform area behind the Depot on Thoreau Street. When the officer approached, the group scattered and left on the ground a tennis ball explosive, like the ones described in various “How To” videos on YouTube.

Officers contacted the Concord Fire Department and State Fire Marshal’s Office, which responded to the scene and determined the tennis ball was safe. There were no injuries and the parking lot was not crowded at the time of the incident, Mulcahy said.

Town Manager Chris Whelan included the incident in his weekly report, posted online on Monday, July 30. He wrote:  

On Friday July 27, officers located a homemade, partially detonated, explosive device in the Depot area of Thoreau Street. Officers contacted the Fire Marshall’s Office, which responded and deemed the device safe. Officers determined that the device was similar to those portrayed in a “how to” video currently circulating the Internet.