Protester Joshua Wilson marches in front of the police department during a rally in Ferguson, Missouri, Sept 26, 2014. [Photo/Agencies]

FERGUSON - A Ferguson police officer was shot in the arm Saturday night after encountering two men at a community center who ran from him and then opened fire during a foot chase, authorities said.

St. Louis County Police Chief Jon Belmar said at a media briefing early Sunday that the officer approached the men around 9:10 pm because the community center was closed. As the officer approached, the men ran away. When the officer gave chase, "one of the men turned and shot," Belmar said.

The officer was shot in the arm and is expected to survive, he said. Belmar did not identify the officer or give further details about his condition. He said the officer returned fire but said police have "no indication" that either suspect was shot.

A search was under way for the suspects early Sunday in Ferguson, the St. Louis suburb that's been the scene of racial unrest in the wake of the August shooting death of an unarmed black 18-year-old by a white police officer.

Belmar said he did not think the officer's shooting was related to two separate protests about Michael Brown's shooting that were going on Saturday night around the same time.

Around midnight at the police station, approximately two dozen officers stood near a group of about 100 protesters who mingled on a street corner, occasionally shouting, "No justice; no peace."

Nearby, part of a road was closed in town as police conducted a search for the suspects. Numerous law enforcement agencies were responding, and police helicopters were canvassing the area.

The officer's shooting comes after Ferguson Police Chief Tom Jackson issued a videotaped apology to Brown's family earlier in the week and attempted to march with protesters, an effort that led to a clash with activists and several arrests on Thursday.

Brown's parents told The Associated Press on Saturday they were unmoved by the apology.

Brown's mother, Lesley McSpadden, said, "yes," when asked if Jackson should be fired, and his father, Michael Brown Sr., said rather than an apology, they would like to see the officer who shot their son arrested.

A county grand jury is weighing whether to indict Ferguson officer Darren Wilson in Brown's shooting.

The Justice Department, which is investigating whether Brown's civil rights were violated, is conducting a broader probe into Ferguson police. On Friday, it urged Jackson to ban his officers from wearing bracelets supporting Wilson while on duty and from covering up their name plates with black tape.

Ferguson residents complained about the bracelets, which are black with "I am Darren Wilson" in white lettering, at a meeting with federal officials this week.

Brown's shooting has also focused attention on the lack of diversity in many police departments across the country. In Ferguson, of 53 officers in a community that is two-thirds black, only three are African-American.

Also early Sunday, not far from Ferguson, an off-duty St. Louis city police officer was injured on Interstate 70 when three suspects fired shots into his personal vehicle, a police spokeswoman said.

Schron Jackson said the officer, who has nearly 20 years of experience, was being treated at a hospital for a minor injury to his arm from broken glass. She said there is no reason to believe the two shootings were related.