New York Police Department (NYPD) said that the axe attack against two of its rookie officers Thursday in Queens was an act of terror by a self-radicalized Muslim convert.

The axe-wielding attacker, identified as Zale Thompson, 32, slashed the arm of one officer while hitting another in the head before he was shot to death, an NYPD spokesman said.

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A 29-year-old bystander was also hurt after getting hit by a stray bullet fired by either of the two rookie officers who were also at the scene.

All wounded were taken to the Jamaica Hospital shortly after the incident, with the 25-year-old rookie officer Kenneth Healey, who sustained a fractured scalp, in a stable condition after undergoing a surgery.

Hours after the bloody rampage, the NYPD declined to officially announce that the attack was terrorism-motivated, although Police Commissioner William Bratton indicated that Thompson may have had links with terrorist organizations based on his online social networking activities.

One of his posts on Facebook referred to an "internal mass revolt" against the United States, reported Fox News.

The suspect claimed that while the U.S. military may be strong, America is largely unprepared for "scattered and decentralized" attacks that could be waged from within. He called for guerilla warfare on U.S. soil, Fox News said.

NYPD stepped up security measures following concerns that the recent attack may stir a series of terror attacks carried out by Islamic State sympathizers in the country, CNN reported late Thursday.   

Commissioner Bratton later said the authorities believe Thompson had acted alone since he appeared to have had no formal affiliation with any known terrorist group, BBC reported.

Thompson, who was described by his father as a "true proverbial loner" was later revealed to have been discharged from the U.S. Navy. His latest social media posts decried the social injustices in the United States and abroad. 

TagsZale Thompson, New York Police Department (NYPD), New York axe attack