A gunman killed 11 people Saturday during a service in a Pittsburgh synagogue.

The shooter made anti-Semitic statements during his attack, CNN reported.

Six other people were wounded, including four police officers, Pittsburgh Mayor Bill Peduto said.

“It sounded like a loud crash in the hallway,” Stephen Weiss of Squirrel Hill told the Pittsburgh Pose-Gazette, who was at the synagogue Saturday morning.

Tyler Pepper, 21, reported hearing several gunshots around 9:45 a.m., the paper reported.

“It was kind of a surreal moment,” he said, later adding that the gunshots sounded like a long gun.

Local officers and agents from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives arrived at a small apartment building on the same street where Bowers may have previously lived according to online records, the Post-Gazette reported. Allegheny County’s bomb squad also arrived at the scene.

The Tree of Life synagogue is more than 150 years old, according to its website, where it calls itself a “conservative congregation” that is “also progressive and relevant to the way we live today.”

“From our warm, inviting and intellectually stimulating atmosphere to our fun adult, children and family programs, it’s the perfect environment to grow a strong faith rooted in tradition,” it said.

A Shabbat service is held at 9:45 a.m. Saturdays.

“These senseless acts of violence are not who we are as Americans,” Gov. Tom Wolf said in a statement. “My thoughts right now are focused on the victims, their families and making sure law enforcement has every resource they need.”

Other officials, including state Attorney General Josh Shapiro and U.S. Sen. Pat Toomey, took to Twitter to say they were monitoring the events in Pittsburgh as they unfolded.

“Synagogues & places of worship are safe havens where communities come together to celebrate, pray, & reflect,” Toomey wrote. “The horrific events that transpired at Tree of Life Synagogue are heartbreaking.”

Philadelphia police said they are monitoring synagogues and other places of worship in the area. The department will deploy officers to places of worship across the city as a precaution.