The RCMP was on the scene of what it called a "serious multi-vehicle collision" on the Trans-Canada Highway in Grand Falls-Windsor Tuesday afternoon.
In a media release, the RCMP said the eastbound lanes on the TCH were impassable between exits 19 and 20 and expected them to remain that way for a number of hours.
Shortly before 8 p.m. Tuesday night the police force advised that all lanes on the TCH had been reopened to traffic, thanking the public for its patience.
There were no details of how many vehicles were involved or the extent of injuries.
The RCMP said an investigation is continuing.
CBC News has asked the RCMP for further details.