UPDATE, 7:04 p.m. - All lanes are now open, we have reports that there was one potential injury. Patch will confirm with Massachusetts State Police sources on Wednesday.
UPDATE, 5:05 p.m.: According to state police, all lanes are open on495 south, but Route 110 remains closed in Chelmsford.
UPDATE, 4:55 p.m.: Massachusetts State Police just sent out this tweet about the crash on 495. The scene remains active, but no one was injured in the crash. Motorists are urged to seek alternate routes.
An earlier story follows:
Chelmsford Patch has received word that a tractor trailer truck has reportedly rolled over on 495 Southbound near the exit for Chelmsford Street.
The truck went through the guardrail down onto the street below, there are currently no reports of injuries, but there are reports of fuel spilled on the scene.