Yesterday, a man wielding a hatchet attacked four New York City police officers, inflicting a head wound on one that left the officer in critical condition. The other officers opened fire on the attacker, killing him and wounding a bystander. At first, the attack could have been chalked up to simple insanity, but then SITE took a look at Zale Thompson’s Facebook page:

The man who attacked New York City police officers with a hatchet before being shot dead was reported to have Islamic “extremist leanings” police and a monitoring group said. The man, identified in the US media as Zale Thompson, had posted an array of statements on YouTube and Facebook that “display a hyper-racial focus in both religious and historical contexts, and ultimately hint at his extremist leanings,” the SITE monitoring group said. … SITE, which monitors radical Muslim groups, said that in a comment Thompson had posted to a pro-Islamic State video on September 13, 2014, he described “jihad as a justifiable response to the oppression of the ‘Zionists and the Crusaders.'”

Police commissioner Bill Bratton advised people not to jump to conclusions:

“There is nothing we know of at this time that would indicate that were the case,” he said. “I think certainly the heightened concern is relative to that type of assault, based on what just happened in Canada and recent events in Israel — certainly one of the things that first comes to mind — but that’s what the investigation will attempt to determine,” Bratton said.

CNN’s Anderson Cooper asked Jim Sciutto, their national-security correspondent, about the issue later last night. Sciutto reports that the NYPD is looking at the same data as SITE:

The New York Daily News notes that Thompson had recently been talking about terrorism with a Facebook friend, according to the police:

Police are investigating the possibility that the attacker killed on a rainswept shopping corridor, identified by police sources as Zale Thompson, 32, had links to terrorism. A Zale Thompson on Facebook is pictured wearing a keffiyeh and had a recent terrorism-related conversation with one of his Facebook friends, according to a police source. Thompson made no statements as he approached the four officers with hatchet in hand on Jamaica Ave. near 162nd St. in Jamaica at 2 p.m., officials said.

According to a CNN report this morning, Thompson had a criminal record and had been discharged from the US Navy for disorderly conduct, and some “commonalities” that have investigators worried enough to issue a warning to all law-enforcement agencies:

And there are uncomfortable commonalities with other Islamist attacks that have law enforcement in New York and Washington on high alert. On a Facebook page bearing Thompson’s name, a warrior masked in a head and face scarf and armed with spear, sword and rifle gazes out at the beholder. The vintage black and white photo is the profile picture of the user, who lives in Queens. A Quran quote in classic Arabic calligraphy mentioning judgment against those who have wandered astray serves as the page’s banner. Some of the user’s Facebook friends posted articles about Thompson’s attack and death, referring to him by name and linking back to the Facebook page. Thompson has been in trouble with the law before. He had a criminal record in California, a law enforcement official said, and the Navy discharged him for disorderly conduct.

This report notes another “commonality” — the somewhat similar circumstances of the murder of UK soldier Lee Rigby in London last December. There are also differences; two men conducted that murder on a single target, which they ran down in a car first. Both attacks, though, involve very personal attacks on figures of authority with cutting weapons by people who have publicly associated themselves with radical Islam. Sciutto notes that it’s these commonalities, plus the proximity of other lone-wolf attacks, that has police leaning toward terrorism as an explanation, rather than workplace violence.