Hwy. 401 has fully reopened between Bloomfield Rd. in Chatham and County Rd. 42 in Tilbury.
The OPP says the crash occurred just before 1pm and involved three tractor trailers.
One person is in hospital with serious, but non-life threatening injuries. Another driver had to be cut from his vehicle, but he was not injured.
Police say two trucks were stopped, possibly because of volume of traffic, when another truck crashed into the back of one of the vehicles, pushing it into the rear of the other.
