FERGUSON, Mo. — As tension remained high here after the killing of Michael Brown, peaceful rallies gave way to more violence overnight.

Amid protests, a St. Louis County police officer shot and critically wounded a man after he had pointed a gun at police early Wednesday, authorities said.

At around 1 a.m., police officers responding to a call that four people wearing ski masks and armed with shotguns were at an intersection in St. Louis, spokesman Brian Schellman said. Police also received calls that shots were fired in that same area.

After police arrived, people began fleeing the scene, Schellman said. One person pointed a handgun directly at an officer, who shot the man, he said. This man, who has not been identified, was taken to an area hospital in critical condition. Police are investigating the incident and recovered a handgun at the scene, Schellman said.

Earlier in the evening, community faith leaders and civil rights activist Rev. Al Sharpton held a massive rally in a local church earlier in the evening to protest the killing of Brown, an unarmed 18-year-old fatally shot by Ferguson police on Saturday. Their purpose was to call for peace and, they hoped, keep residents – many of whom had hit their breaking points after what they describe as years of police mistreatment – out of the violent clashes with officers that have taken place each evening.

“We ask that you all continue to support us in a peaceful manner,” urged civil rights attorney Benjamin Crump, who is representing Brown’s family, as he addressed the standing-room-only crowd at St. Mark’s Family Church about a quarter mile from where Brown was killed.

But even as Crump and other speakers led hundreds in song, dance and chant, local residents were again in a standoff with police in riot gear.

Ground zero for the clashes has been a burned-out Quick Trip gas station, which was destroyed when demonstrations turned violent on Sunday night. Residents and others who travel from other local areas have demonstrated there, holding signs declaring “Guns down for Michael” and chanting, “hands up, don’t shoot.”

But, like clockwork, when the sun goes down each night those remaining on Ferguson’s dark streets are met by heavily-armored police, prompting confrontations and injuries.

Unlike other nights, police moved to clear much of the street during the early evening hours on Tuesday, dispersing most residents and protesters by 11 p.m.

But some lingered in the winding suburban streets near the demonstration site, leading to several more clashes with officers who used tear gas.

In another incident on Tuesday night, a local woman was shot in what police have described as a “driveby shooting.” The woman is expected to survive and police say they are searching for four to five suspects.

The third night of violence comes as community leaders desperately try to contain the rage of residents who are angered by the shooting and the failure of police to release the name of the officer involved.

“Respect the family!” urged Sharpton, who begged the young men in the room to serve as peacemakers. “They haven’t even buried their son – don’t go out there and start stuff in his name.”

Sharpton’s passionate address, often interrupted by the crowd’s chants of “no justice, no peace,” came toward the end of an hours-long service meant to both rally the community and get many off the night streets.

Hundreds attended the rally, dancing and singing in worship.

“Because he lives, I can face tomorrow. Because he lives, all fear is gone…” belted out the worship leader, with attendees responding in turn: “And life is worth the living just because I know he lives.”