There were no immediate reports of shots fired or injuries, and it was not clear whether the person in custody was tied to the original report and whether that report was real or a hoax.
Campus police said they asked the Tampa police bomb team to investigate the belongings of the person taken into custody.
The first call came in at 1:36 p.m. to the Hillsborough County Sheriff's Office, which transferred it to campus police.
Students on campus were interrupted by a loud siren. An announcement over a loud speaker said there was an intruder and students should stay inside and lock their doors, said Amanda Barnes, an 18-year-old international studies major.
Administrators also sent several text messages to students.
"A lot of people were like, 'OK. I'm going to go up to my room, and no big deal,"' Barnes told The Associated Press. "A couple of people were like, 'Oh my God. I'm so scared."'
Another student, Hannah Quill, told the St. Petersburg Times she heard the loudspeaker message too.
"It sounded like one of those tornado alarms up north," she said. "Everyone is like in classrooms on lockdown. I saw quite a few police cars heading towards the front of campus."
At about 3:30 p.m., campus police also reported a man was seen on campus in a black tank top and cowboy hat, carrying a black puppy and a large hunting knife.
Police said officers were en route but it wasn't clear if that was related to the original call.
--- Associated Press writers Michael Schneider in Orlando and Tamara Lush in Miami contributed to this report.