Police were searching for this man.

Police were searching for this man.

Update, 3:10 p.m. Monday: Federal and local authorities gave the all-clear Monday afternoon after searching the Coleman A. Young Municipal Building for a man who passed through security point this morning with a gun at the court entrance of the building.

After the man had already entered the building, security noticed an X-ray image of his bag, which showed a pistol.

City hall, including the courthouse, which is inside, was evacuated while Detroit Police and FBI and ATF agents searched the building for the man, said Sgt. Michael Woody of the Detroit Police Department.

Following the search, it was determined the man was not in the building, and could have possibly slipped out during the evacuation, Woody said.

Authorities announced that city hall is shut until Tuesday. 

Authorities tweeted a photo of the man and continue to hunt for him. It is a felony to bring a gun into city hall and the courthouse, which are gun-free zones.

Detroit Police tweet:

Update: Monday, 1:44 p.m. -- The Detroit Police department wrote on Twitter at 1:07 p.m.:  "People inside of the CAYMC building are being safely evacuated.  The search for the suspect continues."

Police also release a photo of the man they're looking for and the X-ray image of his bag. 

Alexis Wiley, mayoral chief of staff, tweets that municipal center is shut until Tuesday, adding: "Glad everyone's safe!"

Original article, Monday morning:

The Coleman A. Young Municipal Center in downtown Detroit was evacuated Monday morning while police searched for a man with a gun.

Visitors and workers were told to leave after city hall security discovered that a man in his 40s or 50s passed through an X-ray machine with a handgun in his bag, Police Chief James Craig said at a televised media appearance around 10:30 a.m. By the time security discovered it, the man had moved on.

Craig said that authorities were going from floor to floor looking for the man.