CONCORD, N.H. (AP) — A man has pleaded guilty in federal court to calling in computer-generated voice bomb threats to the City Hall in Somersworth, New Hampshire.

According to court documents and statements, City Hall workers received two calls on Feb. 3 stating there was a bomb inside the building. The building was evacuated; it was determined there were no explosive devices.

The calls were tracked to John Rupert, 29, of Scarborough, Maine. Authorities executed a search warrant at his home. They said Rupert said he made the calls because he was angry about an injury he received at a massage parlor in Somersworth.

He is scheduled to be sentenced on July 14.