(CNN) A Chinese college student who made no threats but had alarmed a roommate and a friend with his behavior and bought two semiautomatic rifles will be deported for an unrelated visa issue, University of Central Florida police said Thursday.

Police at the Orlando school said they were first alerted by a campus official in late January that Wenliang Sun, 26, was a "student of concern," UCF police Chief Richard Beary said.

Campus police received information that Sun had altered his appearance and his behavior was changing, the chief said. They contacted the Bureau of Alcohol, Tobacco, Firearms and Explosives and were told Sun owned an AR-15-style rifle and ammunition.

"We know that in today's world that a person in distress who owns a high-powered firearm, we just cannot ignore that," Beary said. "We have a duty and an obligation to make sure our people are safe."

There was "red flag after red flag," that something bad would happen, he added.

Those red flags, the chief said, included Sun being uncommunicative with others and not leaving his room, dying his hair blond, paying for a fast expensive car with cash, and referring to one of his guns as a "sniper rifle."

Beary said Sun also went to a gun range to practice with his rifle and also wouldn't return calls from authorities when they tried to notify him his immigration status was subject to change.

But the chief acknowledged there were no comments in interviews or in reviews of his electronic devices that Sun was planning to harm anyone.

"That's the interesting thing in this case, there were no specific threats. Reiterating that, there were no threats," Beary said.

The chief said the red flags looked at separately might not mean much but when all of them were considered collectively they were concerning.

"I think there was a disaster about to happen and we stopped it," the chief said.

CNN has not yet determined whether Sun has a lawyer.

Banned for not going to class

Sun's non-immigrant student status was revoked when federal authorities learned he wasn't going to class. As an international student, he was required to do so in order to maintain his visa.

Wenliang Sun bought a second rifle in early February after police visited him at his off-campus apartment.

Sun is at a US Immigration and Customs Enforcement holding facility in Macclenny, Florida, according to ICE.

"Under normal circumstances, it probably would not have moved that quickly," an official with Homeland Security said. "He probably would've been placed on notice, and we would have issued him a notice to appear, indicating that he would need to go before an immigration judge in order to deal with his status, or lack thereof."

The official said he didn't know when Sun would be deported.

Sun buys second gun after police visit

When UCF police first heard of Sun's changing behavior, they asked the Orange County Sheriff's Department to go by his off-campus apartment and speak with him.

A slide at the UCF news conference Thursday said no law enforcement action was taken during that January 24 visit.

But campus police received more information and stepped up their investigation of Sun, who was in the second semester of a non-degree program.

Sun wouldn't come out of his room except to eat or do laundry and wouldn't talk to others, his roommate told detectives, according to a police report. Sun also once brought a rifle out of his room, prompting the roommate to report the violation of apartment rules to management.

On February 2 investigators asked Sun if he ever thought of harming himself or anyone else. Sun told the detective "No, never."

Police asked Sun if he would give them his LWRC International 300 Blackout rifle for safekeeping, but the student said no. Sun said the gun was in a storage facility, according to a police report.

As campus police monitored his activities, Sun bought another rifle, a .308 caliber Ruger Precision.

Beary said Sun's recent purchase of a nearly $70,000 Corvette with cash and hair color change were suspicious.

However, police could not detain Sun or take the firearms from him because he had purchased them legally. So they sought help from federal agencies.

Sun was taken into custody February 7 after his immigration status changed and his possession of firearms was illegal, officials said.

On March 21 a federal judge ruled he should be sent home. Sun is not allowed to return to the United States for 10 years.

CNN reached out to the Chinese Consulate in Houston, which has jurisdiction over Chinese citizen affairs in Florida, but it did not immediately respond to CNN's questions about Sun's case.

Other UCF students who own guns shouldn't be concerned, Beary said. He said this case was about patterns and behaviors. The totality of Sun's actions showed he was in crisis, the chief added.