Updated

The University of New Haven student who prompted a lockdown on campus Tuesday was carrying two handguns, ammunition and what appeared to be the same type of assault rifle used by Adam Lanza in the Newtown shootings, police said.

In addition, William Dong, 22, had 2,700 rounds of ammunition at his home along with newspaper clippings about the 2012 Colorado theater shooting that left 12 dead and 70 injured.

Dong, a student at the University of New Haven, was arraigned Wednesday in Milford Superior Court on several charges, including illegal possession of an assault weapon.

Superior Court Judge Frank Iannotti set bail at $500,000 and ordered mental health and medical watches for Dong, The Hartford Courant reported. If Dong posts bail, he will be subject to 24-hour monitoring and must surrender his passport. He is scheduled to return to court Dec. 17

No shots were fired and no one was injured in the scare at the University of New Haven campus in West Haven, which was locked down for more than four hours while police arrested Dong and searched the school grounds. Several nearby public schools also issued shelter-in-place orders as a precaution.

Police said Wednesday that they were not sure why Dong brought the guns to campus, and State's Attorney Kevin Lawlor declined to comment on a motive.

Police described his weapon as a "Bushmaster .223 Assault Rifle with a collapsible stock," – a gun banned under state law, The Hartford Courant reported. A loaded 30-round magazine was in the rifle, police said.

Lawlor said that after Dong was arrested, police searched his home in Fairfield and found 2,700 rounds of ammunition of various sizes and clippings about the Aurora, Colo.,theater shooting.

He said the rifle appeared to be the same kind used by Adam Lanza to kill 20 first-graders and six adults at a school last year in Newtown, about 20 miles away.

Dong was also charged with illegal transport of an assault weapon, illegal possession of a weapon in a motor vehicle and breach of peace, The Hartford Courant reported.

Dong lived with his parents and commuted to school, authorities told the Associated Press. The ammunition and newspaper clippings were found in Dong's room, which was padlocked on the outside to keep people from getting in, Lawlor said.

A customer at a grocery store near the university called 911 shortly after 1 p.m. Tuesday to report a man leaving his car with a gun and walking toward campus, police said. Everyone on campus was advised to get inside. Officers confronted Dong within minutes near a dormitory and arrested him, said Sgt. David Tammaro, a spokesman for West Haven police.

The lockdown was lifted at about 5:30 p.m. Tuesday after police searched the campus. About 6,400 students attend the school, and the majority of its 4,600 undergraduates live in university housing.

"We are all grateful that the situation was diffused quickly and that no one was injured," UNH President Steven Kaplan said in a statement. Gov. Dannel P. Malloy planned to commend first responders Wednesday evening on campus.

The scare was the third at a Connecticut university in the past several weeks

Last week, Yale University in neighboring New Haven was locked down for six hours after a man called police and said somebody was coming to shoot up the campus. Police have said that appeared to be a hoax.

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The Associated Press contributed to this report.