However, the grenade turned out to be a fake, the Detroit Free Press reported.
"It looked like a real hand grenade," Detroit Police Sgt. Stephen Fillare said. "We weren't taking any chances."
Police and fire personnel were called to the building at 7:30 a.m., The Detroit News reported.
"A security guard in the building noticed what he thought was a grenade on a desk in the building," said Detroit Police Sgt. Erin Stephens. "He called authorities and it was determined that it was a fake, a prop."
The building was not evacuated and traffic was maintained on surrounding streets.
Police have yet to determine why the fake grenade was on the desk.