SOUTH PASADENA  (AP) — Police kept watch and jumpy parents escorted students as classes resumed Thursday at a suburban high school that authorities say was targeted for a massacre.

Fifteen officers guarded South Pasadena High School and the district’s four other schools, police Chief Arthur Miller told the Pasadena Star-News. 

For the first time, Cynthia Joseph and her husband escorted their South Pasadena High 11th-grader on the first day of the school year.

“I just want to get a sense that things look safe and secure,” she told the newspaper. “I think there are a lot of people here who feel the same way I do.”

Miller shook parents’ hands.

“It’s not a show of force. It’s a show of support,” he told Joseph. “We’re walking through and are completely invisible. They (students) can care less that we’re here. They’re walking around with their nose in their books, talking to their friends.”

Police on Monday arrested two boys, ages 16 and 17, after detectives monitored their online activity and unraveled the alleged plot to target three school staffers and kill as many students as possible, police said.

Although the South Pasadena teens had no actual weapons and hadn’t set any date for the supposed attack, police say they had researched automatic firearms, handguns, knives, explosives and tactical techniques.

On Wednesday, the two denied Juvenile Court charges that they made criminal threats against another boy after sharing their intentions with him.

Family members of both teens apologized to the community.

The 17-year-old suspect’s father told KCAL-TV that he was upset and disappointed by the allegations, and he thanked the person who tipped off authorities. The 16-year-old’s stepfather, meanwhile, said his son had no intention of actually harming people he loves.

The Associated Press is not naming the parents, because doing so could reveal the identities of the underage suspects.

Sam Hoadley-Brill, a senior at the school, said he has known the 16-year-old boy since middle school and had 10th-grade history with him. While some have said the boy was bullied, Hoadley-Brill told the Star-News that he never saw that happen.

The boy was “not as social as some of the other people were, but he seemed very social with the friends he was with,” Hoadley-Brill said.