Update 3: OPP say the rolling demonstration has left the 401 at highway 49.

Update 2: OPP is urging affected motorists to be patient and drive safely.

Update: Slowdowns happening past Prescott now, heading west.

Original story:

OPP East has tweeted a rolling demonstration is causing slowdowns on Highway 401.

Police say the demonstration is slowing all lanes of traffic to 50 kilometres an hour going westbound.

The slowdowns are currently near Prescott. OPP says they are not sure how far west this will be going.