A man who assaulted a group of NYPD officers with a hatchet before they shot him dead committed "an act of terror," the city's top cop said Friday.

"We at this time believe that he acted alone," Police Commissioner Bill Bratton said Friday. "We would describe him as self-radicalized. We would describe him as self-directed in his activities."

Asked directly if Zale Thompson could be considered a homegrown terrorist or a "lone wolf," investigators said "it appears at this point" that terror was the suspect's "intent," though police stressed the investigation was in its preliminary stages.

Police obtained a warrant to search Thompson's computer for clues about Thursday's daytime assault in Queens, which left Officer Kenneth Healey in critical but stable condition with a head injury and Officer Joseph Meeker with a wounded arm.

Thompson's activity on social media indicated he was a convert to Islam and included rants about injustices in American society and oppression abroad but offered no clear evidence of any direct affiliation with terror groups, police said.

"The common thread going through those conversations are anti-western, anti-government, and in some cases anti-white," said John Miller, the NYPD's Deputy Commissioner for Intelligence and Counter-terrorism.

In recent days, Thompson was "visiting websites that are focused on designated terrorist groups -- al-Qaida, ISIS and al-Shabaab -- as well as looking at different acts of violence," Miller said.

Thompson charged a group of four officers with the 18-inch hatchet as they posed for a picture by a freelance photographer on a Jamaica street corner, striking one officer in the head and another in the arm, authorities said. The two other officers opened fire, killing Thompson.

Detectives say Thompson was still holding the hatchet when he was pronounced dead. The attack -- and the shooting -- happened in less than 10 seconds, Bratton said.

"Those officers exhibited extraordinary bravery and skill in not only taking down an individual who was intent on killing them but also rendering first aid immediately to their fallen comrade," Bratton said.

Moments before the attack, the suspect was seen on a street corner crouching down to pull the hatchet out of backpack before he charged the officers and began swinging the hatchet with a two-handed grip, police said.

Mayor de Blasio called it a "vicious attack" by a "troubled individual."

The two officers who were hurt remained at the hospital Friday. Healey was "recovering but in a great deal of pain," Bratton said.

A 29-year-old woman hit by police crossfire during the attack is also still at the hospital; she was listed in critical but stable condition.

Thompson had six prior arrests in California in 2003 and 2004, mostly on domestic charges, authorities said. His only point of contact with the NYPD was in 1998 -- as a victim of assault. Thompson was involuntarily discharged from the military in 2003 after a three-year stint, possibly because of drugs, officials said. An ax and a hunting knife were recovered from his home.