About 75 employees were evacuated from the Collins Aerospace Recreation Center in Cedar Rapids due to a threat Monday morning.

According to Cedar Rapids police, around 8:15 a.m. someone phoned in an anonymous threat that an explosive device was placed inside the recreation center.

A statement from Collins Aerospace said the threat involved buildings 153 and 154 which includes the Recreation Center, pharmacy, telehealth clinic, physical therapy offices and office space.

Police said they did not find a suspicious device.

Employees returned after about 90 minutes, according to Collins Aerospace officials.