Three junior high school students in Fort Collins have been charged with plotting an attack on their school similar to the assault at Columbine High School, police said.

Two of the Preston Junior High School students were taken into custody Wednesday and charged with conspiracy to commit first-degree murder, said Fort Collins police spokeswoman Rita Davis.

They were being held at the regional Platte Valley Detention Center in nearby Greeley.

A third suspect had already pleaded guilty to a charge of conspiracy to commit first-degree assault, Davis said. She said he was expected to be sentenced in a couple of weeks.

The charges stem from an investigation launched three weeks ago that turned up detailed plans, including graphic drawings of the potential aftermath of the attack with "bodies laying in certain areas, people hanging from rails and someone impaled on a railing," Davis said.

"The target of the attack were the 'prep' students as well as the student population at large," Davis said. She described it as a "Columbine-style" attack.

"These kinds of threats have to be taken seriously and investigated seriously," she said. "When it crosses from becoming a more idle threat to a serious allegation is when they have the means."

Investigators confiscated three guns: a TEC-9 handgun, a double-barrel shotgun and a rifle, as well as ammunition from the home of one of the suspects. Davis said the weapons appeared to belong to the suspect's parents, but the youth had access to them.

A propane tank that the suspects allegedly planned to blow up during the attack was also confiscated, she said.

Police officers were tipped off to the alleged plot by other students on Jan. 12. They were told the suspects were planning to attack on April 24 or 25, possibly because one of those days is known as national "get high" day, Davis said.

The date was also close to the anniversary of the shootings at Columbine in Littleton, where two teen gunmen killed 12 students and a teacher before taking their own lives on April 20, 1999.

Investigators searched the Preston Junior High students' school lockers and homes and interviewed friends and family members. The weapons were confiscated a few weeks ago, Davis said.

Authorities did not anticipate filing charges against anyone else, Davis said.

She said authorities had considered charging the suspects as adults but ultimately decided they would have a better chance at rehabilitation if treated as juveniles.

In addition to the conspiracy charge, Davis said one of the teens was facing a charge of felony menacing in a related case in Larimer County. She did not elaborate.

Residents of Fort Collins were reeling from the news.