[Updated at 5:15 p.m. ET] The major tunnel between Windsor, Ontario, and Detroit was scheduled to reopen at 5 p.m. ET Thursday following a shutdown because of a bomb threat, Windsor police said.

Police "fully inspected" the tunnel before reopening it, Windsor authorities said.

The bomb threat led to traffic backups as drivers on both sides of the border were rerouted.

Employees at the Detroit-Windsor Tunnel received an anonymous phone call around 12:30 p.m. from someone saying there was a bomb in the tunnel, Sgt. Matthew D'Asti with Windsor police told HLN.

Authorities were working together on both sides of the border to investigate and search the tunnel for any possible device, D'Asti said.