CLAYTON, Missouri (AP) -- Authorities said a man charged in the shooting of two police officers in Ferguson during a demonstration had attended the protest earlier that night in the Missouri city, where racial tensions are high following the police killing of a black 18-year-old and a Justice Department report detailing bias within the police and judicial systems.
Multiple activists said the 20-year-old suspect, Jeffrey Williams, wasn't a consistent fixture in their tight-knit group.
The police officers were shot early Thursday as a late-night demonstration began to break up following the resignation of Ferguson Police Chief Tom Jackson in the wake of the Justice Department report.
St. Louis County Prosecutor Robert McCulloch said Sunday in announcing the charges that Williams told authorities he was firing at someone with whom he was in a dispute.
"We're not sure we completely buy that part of it," McCulloch said, adding that there might have been other people in a vehicle Williams is accused of firing from.
Williams is charged with two counts of first-degree assault, one count of firing a weapon from a vehicle and three counts of armed criminal action.
Several activists who've been involved in the protests since the Aug. 9 fatal shooting of Michael Brown by a Ferguson police officer told The Associated Press they were not familiar with Williams.
The Ferguson police department has been a national focal point since Brown, who was unarmed, was killed by now-former police officer Darren Wilson. A grand jury led by McCulloch declined to indict Wilson in November, and Wilson was cleared of civil rights charges by a Justice Department report released March 4.
But a separate Justice Department report found widespread racial bias in the city's policing and in a municipal court system driven by profit extracted from mostly black and low-income residents.
Six Ferguson officials, including Jackson, have resigned or been fired since the federal report was released.
Williams used a handgun that matches the shell casings at the scene, McCulloch said. He also said tips from the public led to the arrest.
County police spokesman Brian Schellman said he didn't know whether Williams had an attorney or when he'd appear in court. A message left at the St. Louis County Justice Center was not immediately returned.
Brittany Ferrell, 26, a protest leader with the group Millennial Activists United, had just left a meeting with other leaders Sunday when word of the arrest circulated. She said no one in the group knew Williams, and they checked with other frequent protesters -- who also hadn't heard of him.
Williams was on probation for receiving stolen property, McCulloch said.
The two officers were released from the hospital later Thursday.
Associated Press writer Heather Hollingsworth in Kansas City, Missouri, contributed to this report.