PORTLAND (AP) — The University of Southern Maine is stepping up security after someone broke into a school-owned van and stole keys that gave access to nearly 50 buildings on the Portland and Gorham campuses.

University officials say the security breach placed millions of dollars of personal property as well as confidential records at risk.

School spokesman Robert Caswell told the Portland Press Herald (http://bit.ly/1afCKnb ) the theft was discovered Tuesday morning.

Locksmiths spent the rest of the day replacing as many locks as possible at affected buildings, with priority given to residence halls to ensure student safety.

An email was sent advising faculty, staff and students to shut down computers, secure personal belongings and lock confidential records.

The theft remains under investigation. The cost of replacing the locks is still being calculated.