BOSTON (AFP/Reuters) - US authorities said on Monday they have arrested a heavily armed Massachusetts man who was building bombs in his apartment and planned to attack a crowded university campus cafeteria on behalf of the Islamic State militant group.

Alexander Ciccolo, 23, was arrested on July 4 for the unlawful receipt of multiple guns, the US Justice Department said in a news release. His indictment was unsealed on Monday. The college he intended to target was not disclosed.

Ciccolo, also known as Ali al-Amriki, is the son of a US police officer and has a history of mental illness. He was on probation for drinking.

FBI agents put Ciccolo under surveillance after being alerted to some of his posts on social media. They watched him buy at least one pressure cooker at a Wal Mart store in North Adams, Massachusetts, according to an affidavit by FBI Special Agent Paul Ambrogio.

Pressure-cooker bombs were used in the attacks on the Boston Marathon in 2013, killing three and injuring 264 people. Ciccolo is accused of being a supporter of Islamic State. Ciccolo told an informant he wanted to build bombs similar to the ones used in the attacks on the marathon, according to the affidavit.

After his arrest, authorities said they searched his apartment and found partially built bombs. "These incendiary devices contained what appeared to be shredded Styrofoam soaking in motor oil," Ambrogio said in his affidavit. Ciccolo allegedly said the Styrofoam would cause the fire from the exploded devices to stick to people's skin and make it harder to put the fire out, according to the affidavit.

Last month, he allegedly told an informant about his intention to travel inter-state to bomb two bars and a police station, before switching his focus to attacking a university instead.

Further concerns were raised by Ciccolo's alleged praise of the June 26 massacre of 38 foreign holidaymakers on a beach in Tunisia, which he is accused of calling a "huge accomplishment."

Ciccolo was arrested after taking delivery of two Glock handguns, a Colt AR-15 rifle and a SigArms high-powered rifle, according to authorities.

After his arrest while at the Franklin County House of Correction, Ciccolo is accused of stabbing a nurse in the head with a pen. The assault left a hole in the nurse's skin and caused the pen to break in half, according to Ambrogio's affidavit.

It is not immediately known whether Ciccolo had an attorney.

His family issued a statement through the Boston police department saying they were "saddened and disappointed" but thanking authorities for preventing "any loss of life or harm to others.

"At this time, we would ask that the public and the media recognize our grief and respect our desire for privacy," they said.

His police captain father was reportedly one of the first responders to the 2013 Boston Marathon bombings that killed three people and wounded 264 others, carried out by brothers of Chechen descent.