Police say three Commack High School students were arrested for hacking into the district's computer systems.

The incident occurred in July, according to police.

News 12 has learned that the teens allegedly changed the schedules of about 300 students and altered two students' grades.

Police arrested Daniel Soares and Erick Vaysman, both of Commack, and Alex Mosquera, of East Northport.

Suffolk police say Soares was the lead hacker. He was charged with burglary, computer tampering, identity theft, computer trespass and eavesdropping. Mosquera and Vaysman were also charged with participating in the security breach.

Police say Soares put an electronic device called a key logger on the school computer. The device can record an employee's username and password. He allegedly used that data to remotely access the school's computers.

Soares was released without bond after his attorney entered a not guilty plea.

"My client maintains his innocence and we're looking forward to a thorough investigation by the district attorney's office," says attorney George Duncan.

The Commack district released a statement saying, "The District continues to cooperate fully with local law enforcement agencies, and our IT Department is working closely with the police to provide digital data to assist law enforcement. In addition, a full electronic security review is underway with a company that specializes in network security."

The students face four to seven years in prison if convicted. They will be back in court in January.