Ferguson police
Members of a St. Louis County investigative team canvass the neighborhood near the Ferguson Police Department, asking residents if they have any information about last night's shooting, in Ferguson, Missouri, March 12, 2015. REUTERS/Kate Munsch

UPDATE: 2:51 p.m. EDT: Police arrested a 20-year-old man in the shooting of two police officers during a demonstration in Ferguson, Missouri, last week, St. Louis County Prosecutor Robert McCullogh said Sunday. Jeffrey Williams was being held on $300,000 bond, charged with assault of two police officers and firing a weapon from a vehicle.

McCullough said the case was developed from information from the public. He said Williams had acknowledged his role in the shootings, and a weapon had been recovered.

"He may have had a dispute with some other individuals. … It's possible he was firing at other people" and accidentally hit the officers, McCullough told a news conference.

McCullough said the investigation is continuing, and it was unclear whether anyone else was involved. Investigators are examining video footage of the event and seeking additional witnesses.

Williams was arrested late Saturday. McCullough said a warrant also had been issued for him for violating probation.

St. Louis County Police Chief Jon Belmar said the injured officers -- one from St. Louis County and one from Webster Groves -- are improving and thanked the public for its assistance.

Original post

St. Louis County Police said Sunday an arrest had been made in last week's shooting of two police officers in Ferguson, Missouri. The shooting occurred Thursday outside police headquarters during a demonstration.

St. Louis County Police Chief Jon Belmar said Saturday that local authorities had "a pretty good idea" where the gunshots that wounded the officers had originated, but did not provide any additional details. He said at the time that an arrest was not imminent.

President Barack Obama condemned the shooting of the two officers during an appearance on "Jimmy Kimmel Live," which aired Thursday. Obama’s comments came even as protests continued outside the police department building in the St. Louis suburb. "What had been happening in Ferguson was oppressive and objectionable and was worthy of protest, but there was no excuse for criminal acts," Obama said. "Whoever fired those shots should not detract from the issue — they are criminals, they need to be arrested."

A news conference is set for 1:30 p.m. CDT at the St. Louis County Justice Center in Clayton.

This is a breaking news story. More details to come.