The protesters of Ferguson appeared to have much to celebrate. The Justice Department had vindicated their claims of police abuse and racial bias. The attorney general had declared, “Those protesters were right.” And on Wednesday, Ferguson’s police chief resigned.

Yet the atmosphere was not celebratory as protesters gathered outside the Ferguson Police Department that night. Before shots rang out early Thursday, striking two officers, several fights erupted in the crowd. And demonstrators on the front lines, police said, seemed, if anything, even more angry and confrontational.

With the protesters finally in a position to claim victory, why did so many of them seem so upset?

Police have yet to identify a suspect in the shooting, or a motive. But what’s clear is that steps taken to improve the treatment of African Americans in the St. Louis suburb have yet to soothe the tensions that flared last summer when a white police officer fatally shot a black teenager on a hot August afternoon.

What’s more, by exposing the ugly details of racial bias among Ferguson officials — and revealing new evidence of widespread civil rights violations — the Justice Department report could be fueling a fresh wave of fury.

“We’re headed in the right direction, but the region has to heal. Things are very, very raw right now,” said John Gaskin III, an activist who is also a member of the St. Louis County NAACP.

The shooting occurred after three days of upheaval in city offices, as the chief municipal judge and the Ferguson city manager resigned. Police Chief Thomas Jackson’s resignation was announced just hours before the shooting.

But Jackson was permitted to step down with one year of health insurance and severance pay, angering protesters who wondered why he hadn’t been fired. Adding to their outrage: a statement by Mayor James Knowles calling Jackson an “honorable man.”

Many protesters fault Jackson for the heavy-handed response to initial protests last summer and for releasing surveillance video showing Brown stealing a box of cigarillos from a convenience store shortly before he was killed. The video was seen as an attempt to smear Brown’s character, a suggestion that he somehow deserved what he got.

“Time and again, politicians said they were in negotiation with Jackson to resign. Time and again, I told them if he resigns with benefits and his head held high, it could even make things worse,” said Justin Hansford, a Saint Louis University law professor and protester.

And then there was the lack of tangible change on the ground. Just before the confrontation at the police department, about a dozen people turned up at city hall to watch the mayor announce Jackson’s departure. The group was not protesting, they said; still, the police turned up — summoned, the activists were told by police, by supporters of Darren Wilson, the officer who killed Brown.

“Even though, yes, there are some strides happening, Ferguson has still shown itself to be a racist police department to the point where if white Darren Wilson supporters say we’re creating a disturbance, the police come running,” said Johnetta Elzie, one of the activists.

Most significantly, the protesters have yet to get what they have yearned for most since Aug. 9: justice for Brown, who was unarmed when he was shot.

Neither a local grand jury nor Justice Department investigators found evidence of wrongdoing on Wilson’s part. Protesters are hoping for a different outcome if Brown’s family files a civil suit.

“What we’re talking about now is changing systems and tickets and all that. That doesn’t necessarily bring peace to the Brown family,” said Antonio D. French, a St. Louis city alderman who followed the incident on social media.

The discontent was palpable Wednesday evening as about 150 people, a mixture of regular protesters and newcomers, took over a parking lot, sidewalks and, at times, the roadway outside the Ferguson Police Department. After months of nightly protests, witnesses described a more agitated environment. A fight broke out between two activists who had feuded on Twitter about opportunism in the movement. Later, a larger scuffle erupted elsewhere in the crowd.

And protesters lit into the officers on duty, a police representative said, yelling in apparent reference to Justice Department revelations of racist e-mails exchanged among cops and other local officials.

“They shouted a number of things,” St. Louis County Police Sgt. Kevin Ahlbrand, president of the Missouri Fraternal Order of Police, said of roughly 20 protesters. “ ‘How many kids did you kill today?’ ‘Are you the [expletive] who wrote the e-mails?’ ”

Protesters say police, too, were particularly aggressive. They appeared to arrest protesters without provocation, a practice called “snatch-and-grab.” At one point, a row of police used shields to push protesters out of the street and onto a sidewalk.

Then came the shooting, which left the protesters and the cops shaken and diving for cover.

“They feel like they were shot at, too, last night,” French said of the protesters. “Many people describe bullets whizzing past their heads.

“It’s scary. And it just shows the crisis that we’re in, when we have our community so broken.”