FERGUSON, Mo. (Reuters) - The shooting of two police officers during a protest rally in Ferguson, Missouri, sparked an intense manhunt for suspects on Thursday and ratcheted up tensions in a city at the center of a national debate over race and policing.
U.S. President Barack Obama and Attorney General Eric Holder condemned the attack on the officers, who were treated at a local hospital and released. Hours after the shooting, police said they were questioning an undisclosed number of people following a raid on a home in the St. Louis suburb.
"What happened last night was a pure ambush," Holder said at a press conference. "This was not someone who was trying to bring healing to Ferguson, this was a damn punk."
With organizers vowing more protests on Thursday night, St. Louis County police and the state's Highway Patrol will take over security from the local force at any demonstrations.
Security was similarly stepped up after rioting erupted in November, when a grand jury brought no charges against a white officer who shot a black teenager to death, an incident that touched off a national wave of demonstrations.
Since 18-year-old Michael Brown's killing in August, protesters have rallied regularly in Ferguson, where tensions between African-Americans and a mostly white police force have smoldered for years.
Thursday's shooting left a 41-year-old St. Louis County Police officer with a shoulder wound and a 32-year-old officer from nearby Webster Groves Police Department with a bullet lodged near his ear, St. Louis County Police Chief Jon Belmar said.
The incident unfolded while protesters were gathered at Ferguson police headquarters to demand more changes in the wake of the resignation of its long-criticized police chief, Tom Jackson, who quit a week after the release of a scathing U.S. Justice Department report that found his force was rife with racial bias.
In one video taken at the chaotic scene, a witness can be heard commenting, "Acknowledgement nine months ago would have kept that from happening."
Investigators wasted no time in bringing people in for questioning. A law enforcement team in tactical gear surrounded and swarmed a home near the scene of the shooting, and television images showed officers breaking through the roof with heavy tools.
Shawn McGuire, a St. Louis County police spokesman, would not confirm media reports that two men and a woman were led away in handcuffs but he said people were taken in for questioning. There were no arrests so far, he said.
Belmar said authorities had possible leads, and said the shooter used a handgun and shell casings had been recovered. Two Missouri congressman offered a $3,000 reward for information leading to an arrest.
The shooting came less than three months after a man ambushed two New York City patrolmen, seeking to avenge the killings of Brown and an unarmed black man in New York.
The White House sent a Tweet that read: "Violence against police is unacceptable," a message echoed by Brown's family. "We reject any kind of violence directed toward members of law enforcement," they said in a statement.
Police and protesters appeared to disagree about where the shots originated. Belmar, who said police did not return fire, asserted the gunfire came from the middle of the crowd.
"I don't know who did the shooting, ... but somehow they were embedded in that group of folks," Belmar said.
Protesters at the scene insisted the shots came from further away.
"The shooter was not with the protesters. The shooter was atop the hill," activist DeRay McKesson said on Twitter.
Jackson, the police chief, was the latest in a string of Ferguson officials who have quit after the Justice Department report, which found the city used police as a collection agency, issuing traffic citations to black residents to boost its coffers. Activists want the city mayor, James Knowles, to step down as well.
Organizers from several St. Louis-area religious, legal and community groups, condemned the shooting but said they would press ahead with street protests.
"We deplore all forms of violence," said Rev Osagyefo Sekou, who was in the crowd when shots rang out. "But we also deplore the findings of the Department of Justice report and the suffering and the misery that this community has endured."
The shooting reignited a long-running debate over race and policing that has sporadically flared on social media since Brown's killing. Among the popular Twitter hashtags was #bluelivesmatter, a play to the #blacklivesmatter slogan popularized by Ferguson protesters.
"A police officer can get away with killing someone on video. Black ppl are often blamed for crimes they didn't commit. But #BlueLivesMatter," read a Tweet from Keziyah Lewis.
Additional reporting by David Bailey in Minneapolis, Fiona Ortiz in Chicago and Carey Gillam in Kansas City; Writing by Frank McGurty; Editing by Bernadette Baum and James Dalgleish