A 13-year-old Westbury boy was arrested Monday and charged with Making a Terrorist Threat, police said.

The teenager used a computer to send threatening messages to two 13-year-old girls that he felt were bullying him, Nassau police said.

The boy logged on to a friend's Facebook account and sent the messages, between Dec. 14 and Dec. 15, police said.

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Detectives traced the messages back to the teenager, police said, and he was arrested at his home.

The boy, whose name was not released by police because of his age, was to be arraigned Tuesday in Family Court in Mineola.