Three teenagers targeted a student and a faculty member to be shot during the opening of school Monday at Lakeshore High, St. Tammany Parish Sheriff Rodney Strain said Friday.

The students also planned to shoot any law enforcement officers who got in their way and then to end their own lives, Strain said in a telephone interview.

The three 15-year-olds, who formed a group called Day Zero, are all in the Florida Parish Detention Center and security will be beefed up at the high school in Mandeville and at other parish schools, Stain said.

The three were arrested after an investigation that began when other students gave information to school officials, who contacted the Sheriff’s Office.

“We cannot say right now that there were absolutely no other members” in the group, but all evidence indicates that all of the students who intended to participate in the shootings have been arrested, Strain said in a telephone interview.

One of the arrested students is from Mandeville and two from Lacombe, the sheriff said.

Strain said that the Sheriff’s Office obtained search warrants and that, based on the available evidence, he and his investigators felt that that the threat was real.