Ann Arbor City Hall was evacuated for more than eight hours Saturday as police investigated a bomb threat.
Although Sgt. Pat Ouellette of the Ann Arbor Police Department said police did not find any evidence of a bomb in city hall — located in the Guy C. Larcom, Jr. Municipal Building — in their search, the building was evacuated until about noon.
Ouellette said at this point there are no suspects in the investigation. The case has been turned over to the FBI’s Detroit field office for further investigation.
Ouellette said two square blocks surrounding city hall, including residences exposed to city hall, were also evacuated.
About 40 people were evacuated from city hall and the surrounding area, including police personnel and residents, he added.
Specifically, police were investigating a filing cabinet located outside Mayor John Hieftje’s office, based on a tip the FBI received.
“We received the information from the Federal Bureau of Investigation at about 3:30 this morning,” Ouellette said.
“The FBI received that information through an overseas source,” Ouellette said. He was unable to comment further on the nature of the source, but said the local FBI office in Ann Arbor informed AAPD of a possible bomb in city hall.
Ouellette said AAPD used six trained dogs to sniff out explosives in order to search the six-floor building.
“The dog went upstairs and did hit on the suspicious filing cabinet,” Ouellette said.
Although nothing was found in the cabinet during the search, Ouellette said even well-trained dogs can occasionally flag an area with no explosives.
He added that the file cabinet was previously located in the basement of city hall where ammunition has been stored, so the dog could have picked up on the scent of some contaminants that had rubbed off onto the cabinet from previous use.
The streets surrounding city hall for a two-block radius in both directions were blocked off while police searched city hall. That led to an influx of traffic problems and congestion exacerbated by the football game, Ouellette said.
“Once football traffic started coming into town it backed up traffic a little bit,” he said.
But he added that radio and TV announcements were made to curb traffic jams.
The local FBI, the Michigan State Police, the Bureau of Alcohol, Tobacco, Firearms and Explosives, the Washtenaw County Sheriff’s Office and the Livingston County Sheriff’s Office assisted AAPD in securing the building, Ouellette said. He added that the Department of Public Safety was not involved because of the football game.
The FBI and city administrators were unavailable for comment.