The University of Maryland campus was under a tornado warning Monday evening, according to UMD Alerts — but the National Weather Service did not issue one.

A tornado warning indicates when a “tornado was sighted or indicated by weather radar,” according to the National Weather Service. At 3:40 p.m., the service did issue a tornado watch for Prince George’s County — which is when tornadoes “are possible in and near the watch area” — but not a warning, which the UMD Alerts indicated.

The first alert, sent by University Police at 5:35 p.m., announced the tornado warning and said alarms would activate across campus. The second, sent at 5:45 p.m., extended the warning to 6:10 p.m., and the third alert, sent at 6:04 p.m., said the warning was canceled “as of 6:00 PM,” and that the “rotation has shifted to the north.”

Alerts also advised what to do during the tornado warning for those who were walking outside, driving, or inside a residence hall, house, construction trailer or other buildings. “Stay away from windows and protect yourself from flying debris with a mattress and thick blanket, if available,” one section said.

The final UMD alert said the tornado warning was issued by AccuWeather, a media company that provides weather forecasting services around the world.

In a statement published at 7:03 p.m., police spokesperson Sgt. Rosanne Hoaas said University Police receives “real-time information” on storms through an agreement with AccuWeather, and police will contact the company to help determine the appropriate response to a storm.

“Based upon the warning and our conversation with their meteorologist, in the best interest of life and safety, we notified our campus community to seek shelter via text and email and sounded the siren,” the statement read.

A similar incident happened in 2011. Based on an Accuweather-issued tornado warning, University Police sent out alerts, set off the alarms and told students to take cover, but a tornado never came, according to Capital News Service.

University buses were temporarily shut down because of the tornado warning, but they are now back in service.