Police in suburban Baltimore are investigating a report of someone with a gun on the campus of Stevenson University.

A message on the university's website Monday says there was a report of an active shooter and asked people to shelter in place until further notice.

The Baltimore County Police Department says on its official Twitter account that the investigation began when two people saw what they thought was a person with a gun and called 911. In other tweets, department spokeswoman Elise Armacost says "no confirmation of armed subject or shooting at this time." She reiterated in a later tweet that police "have not confirmed an active shooter situation at Stevenson U."

Calls and messages to police and university officials were not immediately returned.