Eight people are reportedly dead and more wounded after a gunman opened fire at a synagogue in Pittsburgh on Saturday morning.
Police spokesman Chris Togneri said that a suspect is in custody after being taken to the hospital, adding that there are "multiple casualties inside the synagogue."
Officials said the FBI is taking over the investigation into the shooting, which is being treated as a potential hate crime.
Togneri said that three officers were shot and police were clearing the building. The medical status of the officers who were shot was not immediately clear.
"This is one of the most horrific crime scenes I've ever seen," Pittsburgh Public Safety Director Wendell Hissrich said at an afternoon press conference.
KDKA reported that eight people had been killed and others were wounded, including the officers who exchanged gunfire with the gunman.
Pennsylvania Gov. Tom Wolf (D) wrote on Twitter that he was heading to the synagogue in Squirrel Hill, adding state police were assisting local law enforcement.
"Please stay away from the area and keep the congregants and law enforcement in your prayers," Wolf tweeted.
Pittsburgh City Councilman Corey O'Connor warned residents to stay indoors, saying officers were responding to the situation.
President TrumpDonald TrumpGraham says he hopes that Trump runs again Trump says Stacey Abrams 'might be better than existing governor' Kemp Executive privilege fight poses hurdles for Trump MORE called the shooting "devastating" and suggested that armed guards could have prevented the outcome.
"If they had protection inside, the results would have been far better," Trump told reporters on Saturday afternoon before traveling to a campaign rally in Illinois.
"This is a dispute that will always exist, I think, but if they had some protection inside the temple, maybe it could have been a very much different situation."
Trump called for the gunman, whom he described as a "madman" and "wacko," to receive the death penalty.
"I heard the police did an incredible job, and as you know, numerous police were badly injured. But, again, law enforcement did a fantastic job," Trump added.
We are still learning details about the shooting at the Tree of Life Synagogue in Pittsburgh but it is a serious situation. @PAStatePolice are assisting local first responders. Please stay away from the area and keep the congregants and law enforcement in your prayers.— Governor Tom Wolf (@GovernorTomWolf) October 27, 2018
Watching the events unfolding in Pittsburgh, Pennsylvania. Law enforcement on the scene. People in Squirrel Hill area should remain sheltered. Looks like multiple fatalities. Beware of active shooter. God Bless All!— Donald J. Trump (@realDonaldTrump) October 27, 2018
Police sources told KDKA that the suspected shooter made an anti-Semitic remark upon beginning the attack, shouting "all Jews must die" as he entered the building and opened fire.
Squirrel Hill is considered a historic Jewish enclave in the city of Pittsburgh, and is home to around a third of all Jewish residents in the city.
Police had rushed to the Tree of Life Congregation Synagogue, where attendees had gathered for a Saturday service.
KDKA reported that police received calls from individuals barricaded inside the building.
CNN also reported that investigators were looking at a suspicious package on the first floor of the religious center. At a press conference Saturday afternoon, Togneri would not confirm the status of the package, but noted that no other potential packages or explosives were being investigated currently by police.
Nearby Carnegie Mellon University directed students to avoid the area, citing the police action.
"From Carnegie Mellon University Police Department: A police operation is occurring at the corner of Shady & Wilkins Avenue. Please avoid area until further notice," the university tweeted.
From Carnegie Mellon University Police Department: A police operation is occurring at the corner of Shady & Wilkins Avenue. Please avoid area until further notice.— Carnegie Mellon (@CarnegieMellon) October 27, 2018
— This breaking news report was last updated at 2:49 p.m.