The alerts came suddenly Monday afternoon.

First, a siren echoed throughout USF’s campus around 1:46 p.m.: “Armed intruder on campus. Stay inside. Lock doors.”

Minutes later, the first MoBull text message interrupted cell phones with the same message.

Amid confusion about whether there was an armed intruder with a gun or bomb on campus, the University sent out seven text messages and a number of emergency siren alerts updating students Monday.

USF graduate student Chester Smith was in the Library when he received the first MoBull text message to his phone around 1:50 p.m.

Moments before the text was sent, Smith said police swarmed the library – guns drawn.

“I saw cops bust out with rifles and start sweeping around the building,” Smith said. “It seemed as though (the officers) didn’t know where the person was. They were breeching the area as though they were unaware of his location.”

Smith said his initial reaction was to leave his belongings and evacuate the Library, but he was confused because the MoBull message said to stay indoors.

USF spokesman Michael Hoad said when in an emergency situation on campus, students should always follow police instructions.

Hoad said the siren alert system and MoBull text messaging system are controlled by University Police. He said the system “worked very well.”

“What we want to be able to do is make sure that the police (send the messages) because they are the ones that have the most immediate information,” Hoad said.

The time at which an individual receives a MoBull text message on his or her phone varies depending on the individual’s cell phone company, Hoad said.

Oscar Levy, a senior majoring in mechanical engineering, said he was outside Russell M. Cooper Hall when he received the first MoBull text message.

“I received the message about five minutes after everyone else,” Levy said. “There was some lag involved.”

Levy said by the time he heard the emergency alarm siren, it was too late to get inside any buildings.

“I heard the main alarm and then it reverberated, but everything was locked down, so I just made sure to stay … away from the library,” Levy said.

Levy said he thinks the updates were communicated “fine,” but there was some confusion as to what areas were safe.

“The information got out fine, but the first (text) contained no information telling us where to go,” he said.

Elizabeth Toms, an art student, said she was on her way to the bookstore when she received the first MoBull alert.

“Initially, I blew it off,” Toms said.

Shortly after receiving the text, Toms said she heard the emergency alarm siren, but couldn’t understand it.

“The alarms were definitely loud enough to hear, but it just sounded like a fire truck,” Toms said.

Toms said she thought the emergency alert system “was very effective.”

Hoad said when there’s a threat on campus, University officials take it “very seriously.” He said USF responds to threats similar to an airport’s response.

“If you bring a gun on campus, we are going to respond the way (authorities) would respond in an airport,” Hoad said. “Nobody is going to joke about it, and if you make a threat or joke about making a threat, then we have to respond the way an airport would respond.”

University Police (UP) surrounded a Bull Runner bus near Parking and Transportation Services around 3 p.m. after receiving a call saying a man on the bus claimed to be a gunman with a bomb, said UP spokeswoman Lt. Meg Ross.

Police then arrested Vincent Thomas-Perry McCoy and charged him with falsely reporting the planting of a bomb on state-owned property.

Ross said UP received the first call reporting a gunman near the library at 1:36 p.m, meaning it took just 10 minutes for the first alert to go out.

“We got the alert out pretty quickly,” Ross said. “We were on the scene within minutes.”