University of Minnesota officials closed Coffman Union on Monday morning to “investigate a security threat,” according to a text message alert sent at about 4:30 a.m. The University’s Twitter account relayed a similar message at about 2:45 a.m.

Police were notified of a suspicious package around 11:30 p.m. Sunday, the Star Tribune reported. Now, officers are searching the building to determine whether it’s safe.

The search hadn’t concluded as of 10 a.m., said University spokesman Joe Koktan. The University will release more information once officers are finished canvassing the building, he said.

The package turned out to be a tent bag, according to Kare 11.

Police told students and staff not to enter the building Monday morning, CBS Minnesota reported. Officials didn’t provide an estimate of when the building would reopen.

Buses and Green Line light rail transit are continuing as scheduled, the Star Tribune said.