LEWISTON — A U.S. Postal Service driver was assaulted Tuesday afternoon after his truck struck a young child on Walnut Street.

Police say a 3-year-old boy ran across Walnut Street by himself after exiting Poirier’s Market at about 3:50 p.m., crossing into the path of a postal delivery truck. A rear-view mirror mounted to the driver’s-side corner on the front of the vehicle struck the child, knocking him to the ground, Lewiston police Corp. Jeffrey Baril said.

While a crowd gathered at the scene, at least three men who had witnessed the accident surrounded the truck and began punching the driver, Baril said. The men fled when police arrived, he said.

Neither the driver nor the child were seriously harmed. The boy was treated on the scene and released with no injuries, exiting an ambulance and walking down the street in apparent good spirits with a man identified by police as his father, Roosevelt Spearman Jr.

The driver will not be charged, according to Baril, who said that several witnesses stated that the postal truck was traveling below the posted 25-mph speed limit at the time of the accident. The driver also declined to pursue charges against the men, police said.

“Of course we are gratified that there were no injuries. This summer especially, we urge parents of young children to stay clear of delivery vehicles of any kind,” said Tom Rizzo, spokesman for the postal service in Maine.