The Coast Guard closed the Ambassador Bridge between Michigan and Ontario late Monday in response to a threat.

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Bomb threat closes the Ambassador Bridge between Detroit and Windsor, Ontario

A Coast Guard spokesman says it is "too soon" to determine who sent the threat

A similar threat last week closes the Detroit-Windsor Tunnel

CNN  — 

A major bridge between Detroit, and Windsor, Ontario, reopened early Tuesday after a bomb threat shut it down for more than five hours, police said.

Authorities closed the Ambassador Bridge after a bomb threat was received around 7:15 p.m., according to Sgt. Eren Stephens, a Detroit police spokeswoman.

It finally opened at 1 a.m. after bomb-sniffing dogs “did not detect or find a bomb or suspicious device.”

The U.S. Coast Guard stopped all maritime traffic below the bridge during the incident.

The Ambassador Bridge is the busiest commercial international crossing in North America with more than 10,000 commercial vehicles crossing the bridge on a typical weekday, according to the bridge’s official website.

More than 25% of all commercial goods between Canada and the United States cross the Ambassador Bridge, the website said.

The closing followed last Thursday’s closing of the Detroit-Windsor Tunnel, which also was prompted by a bomb threat.

CNN’s Rick Martin and Julia Greenberg contributed to this report