RIVERTON ? Five teenagers suspected of plotting a shooting spree at their high school will be held for at least 72 hours, a judge has ruled.

District Judge Robert Fleming signed an affidavit early Saturday that said there was probable cause to believe a crime was committed, said Kansas Atty. Gen. Phill Kline. The students, who range in age from 16 to 18, were being held on $500,000 bond each.

Under Kansas law, the students would have been released if Fleming had not signed the affidavit by Saturday morning, Kline said. A next bond hearing was set for 2 p.m. Monday.

Kline said he will determine early next week whether to file criminal charges, and if so, what those charges would be and whether to have the four juveniles tried as adults.

“We’re going to try to get charges filed as soon as we can get it together,” Kline said.

The students were arrested Thursday after details of the alleged scheme appeared on the Web site MySpace.com.

The teens planned to wear black trench coats and disable the school’s camera system before starting the attack between noon and 1 p.m. Thursday, Cherokee County Sheriff Steve Norman said. Sheriff’s deputies found guns, ammunition, knives and coded messages in the bedroom of one suspect and documents about firearms and references to Armageddon in two suspects’ school lockers.

Kline, whose office took over the prosecution at the request of the county attorney, said his office was not prepared to file charges.

“To go forward and compare this to anything else is premature,” Kline said during a news conference in Topeka on Friday. “The evidence is still being obtained.”

The four younger than 18 were being held at a juvenile detention center in Girard. The 18-year-old was in the Cherokee County Jail.

Officials assured the community that the 270 or so students at Riverton High School were safe.

MySpace.com – a social networking hub with more 72 million members – released a statement declining to discuss the case because of the investigation, adding that it has provided users with mechanisms to report inappropriate content.

Riverton is a community of about 600 people in southeast Kansas, near the Oklahoma and Missouri borders.