A central Illinois high school was locked down Tuesday after police received a tip about weapons, and six unloaded handguns were found in a locker, authorities said. Three students were arrested.

Police said they aren’t sure what the teenagers suspected of bringing the guns to Pontiac High School had in mind – there was no ammunition and the guns were left in a locker as classes started eight days into the new school year.

The three teens, all juveniles, were arrested on campus at the 900-pupil school, police Chief Dale Newsome said during a news conference in Pontiac, a town of about 11,800 approximately 30 miles northeast of Bloomington.

Livingston County State’s Attorney Thomas Brown declined to identify the three students because of their ages. He wasn’t sure what charges they could face.

Police locked down the high school about 8:30 a.m. after someone told a police officer based on campus that at least one student had brought guns to school.

“When we are told that student A has guns, we immediately went to student A’s area, his locker, and sure enough, there were guns there,” Newsome said.

“They were not loaded,” police Maj. Jim Woolford said in an interview, adding that he didn’t know why the guns were brought to school. “I don’t know. That hopefully will come out in the subsequent investigation.”

Neither Brown nor Newsome was sure how the students knew each other. Investigators were searching social networking Web sites such as MySpace looking for clues about what was planned for Tuesday at the school, but had so far found none, Newsome said.

After the school was locked down, worried families gathered nearby.

Nancy Wooldridge, whose 17-year-old daughter is a senior at the school, said her husband called her Tuesday morning and told her something was happening there.

“I got up there right away,” she said. “We all decided we weren’t going to leave until we knew our kids were safe.

An officer briefed them regularly, trying to reassure them, Wooldridge said, but “I wanted to feel her in my arms to definitely know that she was OK.”

Five other schools near the high school were locked down as a precaution Tuesday morning, Maj. Woolford said.

Classes are expected to resume at the high school Wednesday. Pontiac District 90 Superintendent Leo Johnson plans a schoolwide meeting early in the day to talk about Tuesday’s events.

Johnson joined the district in July, but said he believed its schools trained for a lockdown – when students can’t leave their classes and entrances and exits are closed – at least twice last year.

Maj. Woolford couldn’t recall students ever bringing guns to a Pontiac school, but said other students have threatened violence.

“We had had several Internet-type threats that never manifested and we made arrests on,” he said, adding that those incidents didn’t appear to be related to Tuesday’s lockdown and arrests.

During Tuesday afternoon’s news conference, a reporter asked Newsome where teenagers could have gotten the six handguns.

Newsome said he didn’t know, but reminded the reporter that Livingston County is farm country.

“It would not be uncommon for the parents of these children to have weapons,” the police chief said.