Cara O'Brien, spokeswoman for Middlesex County District Attorney Gerry Leone's office, said the investigation into the fatal accident that killed Concord resident Martin Redington is ongoing.

She declined to offer any details because of the continuing probe. She also declined to say whether charges will be brought against either of the two drivers involved in the chain reaction accident that unfolded when a landscaping truck struck a sedan that was backing into a parking space on Walden Street in front of the post office.

The sedan bolted backwards at a high rate of speed, jumped the curb and hit Redington as he was walking down the sidewalk. The car accelerated between two parking meters and stopped after crashing backwards into North Bridge Antiques. An inside wall of the shop has a crack in the plaster.

Redington was medflighted to Boston Medical Center trauma unit where he died from his injuries. The other man was only superficially hurt. A helicopter landed at Emerson field to pick up Redington and fly him to Boston. His injuries were believed to be too serious to be handled at Emerson Hospital.

Concord police blocked traffic on Walden between Main and Hubbard streets for most of the day to gather evidence and reconstruct the fatal event. It was a clear day about 1 p.m. when it happened.

O'Brien said she has no timetable for when charges might be brought or not.

The street was busy that day with pre-Christmas shoppers trooping into the post office to mail packages and cards.