Some classes were canceled Monday at Colby College due a bomb threat, college officials said.

But by midday, police found no evidence of any threat to safety on the Waterville campus, and two buildings that had been evacuated were deemed safe to reopen.

In an emergency alert posted online Monday morning, the college said it had received an email saying that a bomb was placed in a library on its campus.

Certain buildings were evacuated and classes in Miller Library and the Bixler Art and Music Center, which houses an art and music library, were canceled, the alert said. Faculty and staff working in the affected buildings were expected to work remotely for the remainder of the day.

The Waterville Police Department completed an initial sweep of Miller Library and found no evidence of suspicious devices, the college said in an update at 10 a.m. Fifteen minutes later, the college issued another update saying police had also tentatively cleared Bixler. Both buildings were still closed as police continued to investigate with the assistance of a police dog.

At 12:45 p.m., the college said in another update that Waterville police had indicated both buildings were safe to return to normal operations.

State police, meanwhile, were investigating who sent the anonymous threat, the college said.

“At this point in the investigation, we do not believe the threat to be credible,” Waterville police said in a statement issued Monday afternoon.

The incident remained under investigation, police said.

A spokesperson for the Maine State Police could not be reached for further details. Colby spokesperson George Sopko referred questions to the Waterville Police Department.

It appeared to be mostly business as usual on campus around 10 a.m. Monday. Some students were outside studying, sitting on Adirondack chairs on the Miller Library lawn.

Staff Writer Amy Calder contributed to this report.