The gunman made anti-Semitic remarks during the shooting, police radio transmissions confirm, and he shot at police who arrived on the scene. A “bearded, heavyset white male” was in custody, CBS affiliate KDKA-TV reported.
Police identified the suspect as 46-year-old Robert Bowers. He was taken to hospital with an injury to the ribcage after a shootout with police. It’s not known whether he had any criminal history.
WATCH: Police say suspect is in custody, multiple casualties after synagogue shooting
Federal prosecutors have charged Bowers with 29 criminal counts, including 11 counts of using a firearm to commit murder, violating U.S. civil rights laws and charges alleging Bowers seriously injured police officers while obstructing the exercise of religious beliefs.
Scott W. Brady, the U.S. attorney for the Western District of Pennsylvania, announced the charges late Saturday, about 12 hours after they say Bowers opened fire inside the Tree of Life Synagogue.
FBI special agent Bob Jones said the Federal Bureau of Investigation, which is leading the probe into the attack, believed Bowers was acting alone, adding: “We have no knowledge that he was known to law enforcement before today.”
Two people are in critical condition — a 70-year-old man with gunshot wounds to his torso and a 55-year-old police officer who suffered multiple extremity wounds. Two police officers and two SWAT team members are in stable condition.
Police said no children were killed in the shooting, amid reports by the Associated Press and other media outlets that a traditional Jewish baby-naming ceremony was taking place.
Bowers was armed with an assault-style rifle and at least three handguns, police said.
WATCH: Synagogue member reacts to deadly mass shooting in Pittsburgh
The University of Pittsburgh Medical Center system said it’s treating multiple victims from the shooting.
Local TV news footage showed police near the synagogue holding rifles and wearing helmets and other tactical gear. Paramedics were also stationed near the synagogue, and police vehicles were blocking some streets in the area.
WATCH: Suspect in Pittsburgh shooting reportedly being treated for injury
The synagogue was packed for a Sabbath service that started at 9:45 a.m. local time, according to the website of the organization, which describes itself as a traditional, progressive and egalitarian congregation.
Pittsburgh Public Safety director Wendell Hissrich fought back tears during a live news conference, telling reporters that he had been to the scenes of plane crashes and other mass fatalities but that the carnage inside the synagogue was “one of the worst” scenes he had witnessed.
Hissrich confirmed that the FBI would take over the investigation into the shooting, which is now being considered a hate crime.
WATCH: Pittsburgh Public Safety Director says the ‘scene is very bad inside’ during emotional statement about Tree of Life synagogue
A social media post by Bowers said a Jewish refugee organization, the Hebrew Immigrant Aid Society, “likes to bring invaders in that kill our people. I can’t sit by and watch my people get slaughtered. Screw your optics, I’m going in.”
The comment was posted on Gab, a Philadelphia, Pa.-based social networking service created as an alternative to Twitter. In a statement, Gab.com confirmed the profile belonged to Bowers.
“Gab took swift and proactive action to contact law enforcement immediately,” it said. “We first backed up all user data from the account and then proceeded to suspend the account. We then contacted the FBI and made them aware of this account and the user data in our possession.”
The tree-lined residential neighbourhood of Squirrel Hill, where the synagogue is located, has a heavily Jewish population.
Jeff Finkelstein, CEO of the Jewish Federation of Greater Pittsburgh, told reporters that on a typical Saturday morning about 50 or 60 people worship at Tree of Life Synagogue.
WATCH: Aerial view of Pittsburgh synagogue shooting scene
Michael Eisenberg, a past president of the synagogue, told the Pittsburgh Tribune-Review that he was about to head to the service when he received a call from a friend telling him about the shooting.
“It’s such a well-meaning community, a religious community, friends, and to see this penetrate that community is jarring. I’m just shaken by it,” Eisenberg said.
He added that the synagogue didn’t receive any threats leading up to the deadly shooting.
WATCH: Officials, community members react to Pittsburgh synagogue shooting
Carnegie Mellon University said all university classes, athletic events and other activities were cancelled for the day.
U.S. President Donald Trump said at a campaign rally in Illinois that the attack was “an anti-Semitic attack at its worst.”
“(Anti-Semitism) cannot be allowed to continue,” he said. “It must be condemned everywhere it rears its ugly head.”
Earlier, Trump said he was monitoring the events and urged people in the Squirrel Hill neighbourhood to stay indoors.
WATCH: ‘If they had protection’ synagogue shooting may not have happened, Trump says
Trump also suggested that whoever was responsible for the killings should get the death penalty, which he reiterated at his rally.
“Those seeking (the Jewish people’s) destruction, we will seek their destruction,” he said. “We have to bring back the death penalty, they have to pay the ultimate price.”
Trump said that he will travel to Pittsburgh, but did not say when.
Pennsylvania Gov. Tom Wolf described the shooting as a “serious situation” and said state police were engaged in helping local first responders.
The New York Police Department said it would be deploying heavy weapons teams to houses of worship across the city as a precautionary measure.
Israel expressed its shock and concern and offered assistance to the local community following the shooting.
WATCH: Israeli prime minister ‘heartbroken’ by Pittsburgh synagogue attack
Minister Naftali Bennett, Israel’s cabinet minister for diaspora affairs, said he is “following the news with concern” and has instructed Israel’s Ministry of Diaspora Affairs to prepare to assist the community in every possible way.
He adds: “Our hearts go out to the families of those killed and injured. May the memory of the murdered be blessed.”
Israeli Prime Minister Benjamin Netanyahu condemned the shooting, which he described as “horrendous anti-Semitic brutality.”
Jonathan Greenblatt, CEO of the Anti-Defamation League, said the shooting was “likely the deadliest attack on the Jewish community in the history of the United States.”
On April 13, 2014, a pair of shootings occurred at a Jewish community centre and a Jewish retirement community, both located in Overland Park, Kansas. A total of three people were killed in the shootings.
— With files from Reuters and the Associated Press