JERSEY CITY, N.J. – The shooting rampage by two gunmen who killed a police officer before opening fire on a kosher supermarket, fueling a three-hour gunfight involving hundreds of rounds of ammunition, is being investigated as domestic terrorism, authorities said Thursday.

"We believe the suspects held views that reflected hatred of the Jewish people as well as law enforcement," Attorney General Gurbir Grewal said at a news conference.

Grewal said investigators are working to determine why Officer Joseph Seals and the JC Kosher Supermarket were targeted by suspects David Anderson, 47, and Francine Graham, 50. Evidence thus far indicates they acted alone, Grewal said. 

The duo are also prime suspects in the slaying of a local man found beaten to death in a car trunk in Bayonne on Saturday, three days before the carnage at the kosher market, authorities said.

Grewal previously had urged caution in making an anti-Semitic link to Tuesday's bloodshed, which began at about noon when police say the duo killed officer Joseph Seals at Bayview Cemetery.

The gunmen then drove a mile to JC Kosher Supermarket where they opened fire on the store, killing three people inside. When the shooting stopped, Anderson and Graham were also dead.

Grewal said evidence indicates the three people in the store were killed "within minutes" of the shooters entering the building. An AR-15, a 12-gauge shotgun and two other guns were found in the store, Grewal said. Another gun was found in the van.

Surveillance video, recorded down the street from the supermarket, shows the van parking across from the store and the duo exit, long guns drawn. Guns pointed at the market, the rampage begins as bystanders flee for cover. USA TODAY has not been able to independently verify the authenticity of the video.

Grewal said both shooters had "expressed interest" in the Black Hebrew Israelite group. The group includes factions that have been designated as "hate groups" by the Southern Poverty Law Center and the Anti-Defamation League. 

The group, whose members believe they are descendants of the ancient Israelites, has been known to shout anti-Semitic rhetoric while congregating on the streets of New York City and elsewhere. But Grewal said no actual links to the Black Israelites had been established.

The leaders of the Israelite Church of God in Jesus Christ in New York, which is among groups connected to the Black Hebrew Israelite movement, said through an attorney Wednesday that they have no connection to the shooting and do not know the suspects.

“There’s no relationship to the events in Jersey City,” said Gerald Lefcourt, the attorney. “There is no connection whatsoever, no knowledge of the individuals” who were named as suspects.

Grewal's assertion that the shooters hated Jewish people comes a day after several other leaders said the same thing. Jersey City Mayor Steve Fulop, citing surveillance video from the scene, had said Wednesday that the shooting was a "targeted attack on the Jewish kosher deli."

Some of the victims live across the Hudson River in New York City, and New York Mayor Bill de Blasio described the attack as a “premeditated, violent, anti-Semitic hate crime.” New York Gov. Andrew Cuomo called it a “deliberate attack on the Jewish community.”

New Jersey Gov. Phil Murphy, standing next to Grewal, said the "attack on our Jewish community... is against all 9 million of us who are proud to call ourselves New Jerseyans."

But Grewal said then that it was too early in the investigation to make such claims. 

Thousands gathered Wednesday for the funerals of victims Leah Minda Ferencz, 32, in Jersey City and her cousin Moshe Hirsch Deutsch, 24, in Brooklyn. Also killed in the store was Miguel Douglas, 49.

Jacob Ferencz, Leah Minda Ferencz’s uncle, said that she and her husband, Moshe, grew up in Kiryas Joel – an Orthodox enclave in Orange County, New York.

“They were a young couple who were dedicated to what they were doing,” Jacob Ferencz said. “They wanted people who moved to Jersey City to have where to shop for groceries.”

Bacon reported from McLean, Va. Contributing: Anthony Zurita, Terrence T. McDonald, Keldy Ortiz, Scott Fallon and Kristie Cattafi, NorthJersey.com; Heather Yakin, (Middletown, N.Y.) Times Herald-Record