St. Louis County police arrested a 20-year-old man who has confessed to shooting and wounding two police officers during a demonstration outside the Ferguson Police Department last week, officials said Sunday. But uncertainty remains about whether Jeffrey Williams, who lives near Ferguson, intended to shoot the officers or whether he was aiming at someone in the crowd of protesters over a personal argument, officials said.

“He has acknowledged firing the shots,” St. Louis County prosecutor Robert McCulloch said at a televised news conference. “It’s possible he was firing shots at someone other than the police but struck the police officers” over a dispute that had “nothing to do with the demonstrations.”