Police say three teenagers planned to detonate a bomb at Connetquot High School in Bohemia.

Authorities say a school administrator was told by students that they overheard three others talking about building a bomb while riding a school bus home on May 1.

Police say the school district provided them with audio and video of the 10-minute bus conversation.

The three teens -- two males and a female who are all 16 years old -- were arrested at school Thursday and charged as adolescents with conspiracy, a felony.

Connetquot High School was evacuated for about 30 minutes while police searched the premises and the teens' lockers.

Each student's home was also searched. Police say they recovered two laptops, three BB guns, a homemade ax and books about serial killers and forensics, along with "The Anarchist Cookbook," which includes bomb-making instructions.

Police say they believe the teens intended to follow through with their plan, based on what they found.

The teens' identities have not been released.

The school district sent a letter to parents letting them know about the arrests and assuring them that it's an isolated incident.

Potentially deadly attacks at Connetquot High School have been thwarted in the past. In 2010, prosecutors say a teenage girl and her then-boyfriend tried several times to buy guns but were unsuccessful. Dana Saltzman, who got probation, said Christopher Franko had actively searched online how to make bombs. Franko was sentenced to three to nine years in prison.

And in 2007, two teens were arrested after a notebook called "The Journal of the Dark" was found in a parking lot in Bohemia. It contained graphic details and blueprints for a Columbine-style killing spree at Connetquot High. A 15-year-old pleaded guilty and served one year in a juvenile treatment facility. A second teen, then-17-year-old Michael McDonough of Holbrook, pleaded guilty as well.