All eastbound lanes of Highway 401 were closed Tuesday west of Ayr due to a single-vehicle crash.
The crash occurred around 4:15 p.m. at the Nith River bridge.
OPP say it involved a charter bus carrying 30 Grade 8 students from Columbus, Ohio and three adult chaperones.
The group was on their way to Toronto.
Minor injuries were reported, including to one chaperone who was taken to hospital for treatment.
By 5:30 p.m., one lane had reopened, with the rest expected to follow suit later in the evening.
