(AP) — Authorities in Lincoln have arrested an 18-year-old high school student after homemade explosives were found in his car at school.

Lincoln police say George Carl Chen was taken into custody Monday. He faces felony charges of unlawful possession of explosive materials and possession of a destructive device. Court records do not list an attorney.

Police say they discovered on May 7 more than 160 rifle rounds and 26 homemade firecrackers in Chen’s car at Lincoln East High School. Another 50 rounds were found in his backpack.

Chen told investigators he uses the rounds for target practice. He said the fireworks were from Fourth of July celebrations. Officer Katie Flood says there’s no evidence that Chen meant to harm anyone at the school.