According to KTVI, the incident happened during a traffic stop shortly before 11 a.m. in Ballwin, some 25 miles from Ferguson, Missouri. The St. Louis suburb was the site of major protests following the police killing of unarmed, 18-year-old Michael Brown in 2014, sparking nationwide unrest over police brutality and systemic racism in policing.

The officer’s condition is unknown, but a suspect is in custody.

The incident comes hours after at least one sniper killed five Dallas police officers and wounded another seven at the site of a Black Lives Matter protest following the killing of two Black men by police. Alton Sterling was shot in the chest by police in Baton Rouge, Louisiana on July 5, and Philando Castille was killed during a routine traffic stop in St Paul, Minnesota a day later. Videos of the incidents went viral on social media, sparking outrage at the latest killing of Black civilians by U.S. police officers.

Dallas Police Chief David Brown said the suspected shooter, Micah Johnson, was upset about the recent police killings and said the 25-year-old "wanted to kill white people, especially white officers."

Brown said police used a robot carrying a bomb to kill Johnson after a standoff.