Police said a school resource officer received information that Chen might have brought a gun to school, and the officer and school security went to a classroom to get Chen. Officers escorted Chen to a school office and asked if he was armed.
Officials said that during that interview, Chen said he had a handgun in his book bag and a knife in his shirt pocket. The officer recovered both the gun and knife and arrested Chen about 2:20 p.m., police said.
Authorities charged Chen with possession of a handgun, possession of a firearm by a person under 21 years old and possession of a firearm on school property.
Police say they are continuing to investigate how Chen got the gun and why he brought it to school.