By Anne Baker

A veteran Boston firefighter died Friday afternoon and another was seriously injured when a fire truck tore down Parker Hill Avenue and crashed into Mission Park, an apartment complex on Mission Hill, a fire official said.

Lt. Kevin M. Kelley, who had worked at Ladder 26 near Wentworth Institute of Technology for 20 years, was in the passenger seat of the fire engine returning from a routine medical call when the truck crossed Huntington Avenue and hit the building at about 2:30 p.m, said Steve MacDonald, a fire department spokesman. He said Lt. Kelley died instantly, although the cause of his death is still unknown.

He said there has not been a determination for the cause of the accident, despite local media reports that the engine’s brakes failed. Three other firefighters, four children and three adults were also sent to the hospital for injuries, treated and released. A section of Huntington Avenue near the accident site was closed for about 10 hours after the accident and service on the E train from Northeastern to Heath Street was stopped until Saturday morning, MacDonald said.