PORT HURON, Mich. (AP) — About 13,700 gallons of sulfuric acid has spilled from one of about 40 freight train cars that derailed in an international tunnel connecting Michigan and Canada.

Canadian National Railway spokesman Jonathan Abecassis says the chemical has been contained Friday at the site and poses no threat to public safety.

Abecassis said the derailment occurred about 4:30 a.m. Friday and is under investigation. No injuries were reported.

The tunnel beneath the St. Clair River connects Port Huron to Sarnia, Ontario. The train was in Port Huron at the time of the derailment.

Port Huron City Manager James Freed said the wreck caused "significant damage" to the track. It was not clear when the tunnel would reopen.

Freed said trains are being rerouted to a crossing in Detroit.