SAN ANTONIO (AP) — A 17-year-old boy who hid a loaded AK-47 assault rifle in a school bathroom and two loaded handguns in his backpack intended to “commit a violent act,” a school official said, but the plan was foiled when his parents discovered the weapons missing at home and alerted school administrators.

The unidentified boy was taken into custody after he was found at Madison High School with two loaded handguns and ammunition stuffed into his backpack. North East Independent School District spokeswoman Aubrey Chancellor said the boy admitted to hiding the AK-47 in a trash can in the bathroom.

She said the assault rifle was placed in the bathroom either before school began or just as classes started, but Chancellor said it’s not clear how the boy was able to sneak the weapon into the school. He also was found with a 12-inch knife.

The school with 3,200 students was placed on lockdown shortly after 10 a.m. Monday. After the campus was searched, the lockdown ended at 11:30 a.m. There were no reports of injuries or shots being fired.

The boy’s parents awoke about 6 a.m. to find the boy missing, Chancellor said. They called San Antonio police to report him as a runaway. When they discovered the missing weapons, they rushed to the school to speak with administrators, she said. Their son, a sophomore, was pulled from class and the handguns and ammunition were discovered in his backpack. His parents then asked what he did with the AK-47.

Chancellor said when he was confronted by administrators and his parents, the boy said he intended to make a series of demands during morning announcements. If those demands weren’t met he vowed to use the weapons to “commit a violent act.”

The 17-year-old’s demands weren’t clear Monday.

Police intend to charge him as an adult, on one count of making terroristic threats and another count of being in possession of weapons in a prohibited place, Chancellor said.

“We can have every safety tool possible but at the end of the day what it comes down to is students, staff, parents, everyone being alert,” she said. “And if something seems out of place then letting someone know. And that’s exactly what happened in this case.”