Early investigative details suggest a virulent anti-Semite needed only a few minutes, three pistols and an AR-15 semi-automatic rifle to carry out the deadliest attack on Jews in U.S. history, killing 11 people inside a Pittsburgh synagogue.

All the victims were at services inside the Tree of Life synagogue when Robert Bowers allegedly burst in through an open door, screaming anti-Semitic slurs and shooting.

“They’re committing genocide to my people,” the suspect told a SWAT officer after being shot and captured, according to a federal criminal complaint released Sunday. “I just want to kill Jews.”

Pittsburgh Mayor Bill Peduto called the attack the “darkest day of Pittsburgh’s history” after the victims’ names were read at a news conference Sunday morning. He also disputed President Donald Trump’s suggestion that the synagogue should have had armed guards.

“The approach we need to be looking at is how we take the guns — the common denominator of every mass shooting in America — out of the hands of those looking to express hatred through murder,” Peduto said.

The shooter targeted a congregation that is an anchor of Pittsburgh’s large and close-knit Jewish community, a massacre that authorities immediately labeled a hate crime as they investigated the suspect’s history of anti-Semitic online screeds.

The FBI said Bowers, 46, was not previously known to law enforcement before he drove to the synagogue on Saturday morning, as three different congregations celebrated the Jewish Sabbath inside.

He allegedly walked through an unlocked door around 9:45 a.m., armed with a Colt AR-15 rifle and three Glock .357 pistols — all four of which fired, police said, as he moved around the large building, screaming about Jews.

Bowers roamed the maze-like building, authorities said, gunning down groups of worshipers as he came across them.

Among the eight men and three women killed were Rose Mallinger, 97; Cecil and David Rosenthal, two brothers in their 50s; and Bernice Simon and her husband, Sylvan, both in their 80s. Also killed were Joyce Fienberg, 75; Richard Gottfried, 65; Jerry Rabinowitz, 66; Daniel Stein, 71; Melvin Wax, 88; and Irving Younger, 69.

Two other worshipers were wounded in the initial shooting rampage, which lasted about 10 minutes before someone called 911, police said. Two police officers arrived at the synagogue within a minute of the call and encountered the gunman at the synagogue’s entrance.

“He had finished, and he was exiting the building,” FBI agent Robert Jones told reporters. “Had Bowers made it out of that facility, there is a strong possibility that additional violence would have occurred.”

Instead, authorities say, Bowers exchanged gunfire with the two officers, shooting one in the hand; the other was injured by shrapnel.

He fled back inside the synagogue, and a small SWAT team assembled to pursue him and try to rescue the wounded inside.

Bowers shot two more officers — multiple times each — during a brief standoff on the building’s third floor, according to criminal complaints.

The final casualty count was 11 people killed and six wounded, including the four officers.

The suspect was also shot several times before he surrendered inside the building. He remained in fair condition and in federal custody on Sunday.

Two of the wounded officers remained in stable condition in a hospital Sunday morning. As they recovered, Jewish leaders and local, state and federal officials detailed what happened in the shooting’s aftermath, as well as what is still to come.

Authorities have closed off the synagogue and much of the surrounding area, although they do not believe the suspect had accomplices.

As news of the shooting spread, police locked down other, nearby synagogues. Police also raced to synagogues in Washington, New York City, Chicago and Los Angeles to provide additional security.

Investigators worked through the night at Tree of Life processing what Jones called “a large and complex crime scene.” They also consulted with rabbis to identify the bodies, which remained in the building until Sunday.

Bowers’ house in the Baldwin neighborhood was searched, and investigators have begun to scour his social media feeds. These may include a since-deleted Gab account in which a user with Bowers’ name compared Jews to Satan and complained that Trump’s “Make America Great Again” movement cannot succeed so long as Jews “infest” the country.

Bowers is expected to have his first court hearing Monday. He faces at least 23 state charges, including homicide, attempted homicide and aggravated assault against police officers.

He faces an additional 29 federal charges accusing him of civil rights and hate crimes.

Like the prime minister of Israel, the pope and political leaders across the world, Trump has condemned the synagogue attack. He ordered flags flown at half-staff through Wednesday.

At a political rally on Saturday evening, Trump called the massacre “an assault on humanity” that “will require all of us working together to extract the hateful poison of anti-Semitism from our world.”