There's no confirmation that any gunman is actually there, but authorities have locked down the main campus of the University of South Florida in Tampa this hour so that police can search buses and possible hiding spots near the library.
The St. Petersburg Times reports that someone called the Hillsborough County Sheriff's Office around 1:36 p.m. ET to report they had seen an armed person near the library.
On MSNBC a moment ago, live video from the scene showed police putting a man into a cruiser.
Update at 4:06 p.m. ET: The St. Petersburg Times now reports that while a male was arrested, "Tampa police spokeswoman Laura McElroy said the individual has told authorities it was a hoax. McElroy said the man stood up on one of the campus shuttle buses and claim(ed) to be the individual campus police were searching for. After the man surrendered, he told USF police that he was joking when he said he was the suspect, she said."
Update at 3:33 p.m. ET. It's not clear whether this is related or not, but the university just posted this alert:
White male subject seen in Cooper Hall area in black tank top, cowboy hat, carrying black puppy and large hunting knife. Officers in route.
Entire Tampa campus remains on alert. Stay inside. Lock doors. Report any suspicious activity.
Update at 3:15 p.m. ET. The latest news on the university's website:
UPDATE - TAMPA CAMPUS, 3:06 P.M. — USF Police has one subject in custody and has requested the Tampa Police Bomb Team to respond regarding the subject's belongings. Check back for updates.
Update at 3 p.m. ET. The university now has this posted on its website:
EMERGENCY UPDATE: TAMPA CAMPUS, 2:48 P.M.
USF Police continuing to investigate the report of an armed subject on USF Tampa campus. The report that a subject armed with a bomb and gun in the area of the main library came in at 1:36 p.m.
USF Police have since received a report of a subject on a bus in the area of Parking and Transportation Services on the USF Tampa campus. Police are on the scene.