The deadly rampage that ended with one police officer slain and three bystanders killed at a kosher market in New Jersey is now being treated as an act of domestic terrorism, authorities said Thursday.

Investigators believe the two attackers were “fueled both by anti-Semitism and anti-law enforcement beliefs,” New Jersey’s attorney general, Gurbir S. Grewal, told reporters at a news conference.

As a result of the evidence so far, the FBI was investigating the violence as “a domestic terrorism incident with a hate crime bias,” said Gregory W. Ehrie, the special agent in charge of the bureau’s office in Newark, New Jersey.

After initially calling the attack on the kosher market in Jersey City on Tuesday a random act, investigators said that the store had been deliberately targeted but did not explicitly say it was motivated by anti-Semitism.

Even as it emerged that one of the two attackers, David N. Anderson, had published anti-Semitic posts online and had ties to a movement that has expressed hostility toward Jews, federal and state authorities shied away from calling the assault a bias crime.

But Thursday, Grewal confirmed that investigators believed Anderson and his accomplice, Francine Graham, both of whom were killed in the firefight, held views that “reflected hatred of the Jewish people, as well as a hatred of law enforcement.”

He also said that investigators had found four firearms belonging to the assailants inside the supermarket, including an AR15-style weapon and a shotgun, as well as an additional gun and a pipe bomb inside a rental van the suspects had been driving.

“They had a tremendous amount of firepower,” Grewal said.