WASHINGTON, USA (AFP) — Two police officers in the US flashpoint town of Ferguson were shot early yesterday during the latest protest over the treatment of blacks by the mainly white police force.

One officer was shot in the face and the other in the shoulder as a protest rally outside the police station in the Missouri town was dispersing, St Louis County police chief Jon Belmar told reporters.

He said the officers, aged 32 and 41, were conscious and that their injuries were serious.

Ferguson, in recent months, has been one of the hot spots for the long-standing US problem of harsh treatment of young black men by mainly white police.

Earlier in the day, the Ferguson police chief resigned over a scathing US Justice Department report into the fatal shooting of an unarmed black teenager, Michael Brown, by one of his officers back in August.

The town is so tense that any new development in the Brown case has proved enough to bring protesters out on the street. The latest twist was the resignation of the police chief and other city officials –that gesture apparently insufficient for people enraged over the death of Brown.

Brown was killed by white police officer Darren Wilson, igniting angry protests and a national debate about race and law enforcement in America. Wilson was not charged in that death.

Belmar said the Wednesday protest was dispersing when at least three shots were fired.

“The police officers were standing there and they were shot. Just because they were police officers,” Belmar told reporters at the scene of the incident.

About 60 or 70 protesters had come to the police department. Some blocked roads and sidewalks, and this caused authorities to bring in officers, some in riot gear.

Witness Markus Roehrer told CNN that the atmosphere at the protest was tense and that when he first heard the gunfire he thought it might be firecrackers.

“When I saw the cops go down, I said this is far worse,” he told CNN.

CNN broadcast blurry amateur video in which gunshots are heard and protesters run away in panic. A moaning voice is heard. Then police are seen crouching with weapons drawn.

Belmar said it was not really clear where the shooting came from.

But Roehrer said the sound came from some distance behind the small group of protesters, which he estimated at about 40 when the gunfire rang out.

“To put this on the protesters would be totally unfair,” he told CNN.

The protest came hours after Ferguson police chief Thomas Jackson became the latest prominent official in the St Louis suburb to stand down, seven months after Brown was shot and killed. Jackson had been on the job since 2010.

The Justice Department last Wednesday said it lacked sufficient evidence to prosecute officer Wilson on federal civil rights charges over the August 9 death of 18-year-old Brown after an altercation on a quiet residential street.

But it condemned Ferguson’s city hall, police department and municipal court for racial bias in targeting its African-American majority as a means to generate revenue.

Brown’s family has indicated it intends to file a civil lawsuit against Ferguson and Wilson, accusing them of unlawful death.

“Michael Brown’s mother and father are relieved that actions are being taken to address the very disturbing findings in the Department of Justice report,” family lawyer Benjamin Crump told CNN.

Other Ferguson officials to resign have included Ferguson’s municipal court judge, two long-time police commanders — including Wilson’s supervisor — and, on Tuesday, its city manager.

Ferguson’s court clerk was meanwhile fired over emails that smacked of racism.

Still in office is Ferguson Mayor James Knowles. He has promised root-and-branch reforms in the community of 21,000, in which two in three residents are African American.

Wilson, no longer with the overwhelmingly white Ferguson police force, said he shot Brown after the youth — a suspect in a corner-store shoplifting — tried to grab hold of his firearm.

Others insist that Brown had put his hands up in a gesture of surrender when Wilson opened fire.

A grand jury in November chose not to indict Wilson on murder or manslaughter charges, reigniting protests that sometimes turned violent.

Police departments around the United States have come under intense scrutiny over the deaths of African-Americans — from New York, where Eric Garner died after he was put in a chokehold during a sidewalk arrest, to Madison, Wisconsin where protests continued Wednesday after Friday’s shooting death of an unarmed teenager.

Outgoing federal Attorney General Eric Holder has threatened Ferguson with a lawsuit if it fails to fulfill a set of recommendations to overhaul its law enforcement and municipal court system.