DETROIT -

Ambassador Bridge shutdown 4 The Ambassador Bridge is now reopen after shutting down after authorities received a threat on Monday.

The bridge reopened around 1 a.m. Tuesday. No device was found.

The Detroit side of the bridge was completely shut off to traffic Monday evening. The U.S. Coast Guard was working with Canadian officials to get the bridge shut down on that side, too.

The U.S. Coast Guard also was securing the Detroit River. A stretch of the river was shut down while the bridge was shut down.

Images: Traffic to Ambassador Bridge blocked off on Detroit side

According to Mickey Blashfield, of the Detroit International Bridge Company, a bomb threat was phoned in at 7:52 p.m. Monday. The threat was on the American side of the bridge. The Detroit police are the lead agency in the investigation. Police said the call came from the city of Detroit. The caller said there was a bomb on the bridge and it would go off in 10 minutes.

Blashfield said Monday night that he expected the bridge to be reopened soon. He said the threat was called into the Detroit Police Department. Homeland Security notified the DIBC. Bridge security and Detroit police worked together to complete an inspection.

Truckers were told they should expect to wait hours to cross the bridge while traffic was backed up for miles on both sides. The trucks cannot cross the Detroit River through the Detroit-Windsor Tunnel, so they either have to wait at the Ambassador Bridge or drive north to Port Huron to cross at the Blue Water Bridge.

Ambassador Bridge shutdown DIBC President Dan Stamper released the following statement Monday night:

"Similar to the Detroit-Windsor Tunnel threat last week, Detroit police received a threat against the Ambassador Bridge tonight at approximately 7:55 pm. We take any threat very seriously, and set in motion the security measures the bridge has had in place since 9/11, staying in constant contact with first responders. We expect that after a thorough inspection, the bridge will open soon. We have thoroughly examined the bridge and await the completion of Detroit Police exercises for the bridge to be opened.

We cannot confirm, but suspect, that this has something to do with Canada’s disinvestment at the border by cutting back on customs’ agents. The Detroit International Bridge Company remains vigilant in its efforts to ensure that all those who cross the Ambassador Bridge remain safe."

Watch: Uncut: Traffic to Ambassador Bridge blocked due to threat

The Detroit Fire Department also said the call was received at 7:52 p.m.

Detroit police, along with other agencies, were searching the bridge. Police inspector Don Johnson said they were meticulously searching the bridge with dogs. Johnson said they would take their time to ensure the bridge is safe to travel across.

Related: Detroit-Windsor Tunnel reopens after bomb threat

A bomb scare shut down the Detroit-Windsor Tunnel for several hours Thursday afternoon.

Ambassador Bridge shutdown 2