Residents of this pastoral suburb of roughly 8,000, who endured a lock-down that lasted more than six hours and included the closing of schools, were left mystified and saddened as to how and why one of their own concocted such a story. The officer — a 24-year-old who was working as a full-time dispatcher and as a part-time patrolman — was scheduled to begin training for a full-time patrol position soon, according to police.

As the investigation continued, officials said the officer would be fired and could face criminal charges as early as next week. His police SUV crashed into the woods around 2:30 p.m. Wednesday off Forest Road, caught fire, and was destroyed. The officer said the vehicle had been hit by gunfire from a white man driving a dark-colored pickup truck.

But investigators determined that the shots were fired by the officer himself and there was no pickup truck driver, said Millis's acting police chief, Sergeant William Dwyer, who wore a grim expression as he briefed the media during an afternoon news conference.