The Detroit-Windsor Tunnel reopened Tuesday after it was shut down because of a suspicious package.
“Incident has been resolved,” the Windsor, Ontario, Police Department wrote on Twitter.
Staff Sgt. Jason Crowley told CNN an explosive disposal unit neutralized a “commercial-grade smoke device” found in a car entering from the Canadian side. The device had components of a firework or smoke grenade, he said.
Brass knuckles were also found in the car, said Crowley.
According to the spokesman, two men were detained by customs officers during an investigation, which is ongoing. He did not identify those men, and no charges have been filed.
The smoke device did not pose a threat to the public, Crowley said.
The Detroit-Windsor Tunnel connects Detroit, Michigan, with Windsor, Ontario, in Canada.