11 people were killed and several others were injured during the attack in the neighborhood of Squirrel Hill, which is a few miles from the Steelers' practice facility.
Players and fans at Heinz Field bowed their heads and stood in silence for approximately seven seconds before the contest against the Browns. The scoreboards also went dark during the moment of silence.
"On behalf of the entire Steelers organization, we offer our support and condolences to the families of the attack of peaceful citizens worshipping at the Tree of Life Synagogue," team president Art Rooney II said in a statement Sunday morning.
"Our hearts are heavy, but we must stand against anti-Semitism and hate crimes of any nature and come together to preserve our values and our community."
"Prayers up for Pittsburgh," Brown wrote.
Prayers Up for Pittsburgh 🙏🏾— Antonio Brown (@AB84) October 27, 2018
"Praying for the congregations, the Pittsburgh communities, the Squirrel Hill neighborhood, the first responders and our leadership, as they find a way to come together and hold each other up during the horrific event that took place at Tree of Life this morning," Bettis wrote.
Defensive end Cam Heyward wore a T-shirt featuring a heart around the word "Pittsburgh" as he entered the stadium.