FORT WORTH, Texas — The University of North Texas Health Science Center at Fort Worth issued an urgent warning about the "potential for violence" Wednesday afternoon that resulted in an "immediate lockdown" for about two hours before an all-clear was sounded. 

Personnel were advised to "seek shelter immediately inside a secure location." 

The school later said that camera equipment being carried by a person had been mistaken for a weapon. 

Aerial views of the campus showed it was surrounded by dozens of police cars and at least one ambulance was standing by.  Heavily-armed police were on patrol.

Fort Worth police told KXAS they responded to calls reporting a person on campus with a weapon. Nothing suspicious had been found as of 1:45 p.m., and the school issued an end to the "Red Alert" at 2:24 p.m.

Additional details were not immediately available.