"Motorists heading to the Ambassador Bridge border point on #Hwy401 westbound are advised to plan an alternate route to the border via #HWY402 due to ongoing demonstration activity in the Windsor area", the police said on Twitter.
Canadian broadcaster CBC News reported that the bridge was blocked on Monday night. The report cited protesters as saying that they were not going to leave the bridge but left one line open for traffic to cross the US-Canada border. Nevertheless, the traffic is reportedly heavy, with some trucks jammed on the bridge for hours.
The broadcaster also cited the Canada Border Services Agency as saying that all motorists were advised to cross the border via the tunnel 1.8 miles east of the bridge.
Protests have been sweeping across Canada since mid-January, with thousands of truck drivers and other protesters opposing vaccine mandates for truckers crossing the US-Canada border. Protests this weekend featured political slogans against Canadian Prime Minister Justin Trudeau. The Ottawa mayor declared a state of emergency on Sunday, and Trudeau was relocated from Ottawa to his nearby summer residence out of safety concerns.