Windsor police dealt with what was called an "active investigation" at a border crossing on Friday afternoon.
Few details have been released, but officers responded to the Canadian point of entry at the Ambassador Bridge at around 3:30 p.m.
One person has been arrested.
Police say there is no threat to public safety.
According to estimates on border wait times provided by the Canada Border Services Agency, the wait time to enter Canada for commercial vehicles was at least one hour and 15 minutes as of 8 p.m. Friday. Personal vehicle traffic was back to normal.
Commuters were also urged to enter Canada via the Windsor-Detroit Tunnel or the Gordie Howe International Bridge.
More to come.