Protests continue in Ferguson after police officers are shot

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(NBC NEWS) - Protesters gathered near the Ferguson, Missouri, police department Thursday and chanted slogans like "the whole damn system is guilty as hell," a day after 

two police officers were shot

 as another demonstration began to disperse.

The crowd of more than 100 protesters appeared to be peaceful. Demonstrators briefly blocked a road and rebuffed police who asked them to leave. About 20 police officers were visible, NBC station KSDK reported.

Earlier, a group of religious leaders and demonstrators held a candlelight vigil and prayed not only for the wounded officers and their families, but for protesters and for the nation as a whole. Police are still searching for suspects.

"Whoever was the culprit last night did not come from this community," Rev. Traci Blackmon said at the vigil, noting that no police officers were shot during months of protests, even when anger over the fatal police shooting of Michael Brown was at its height. "We will not be moved. We will not give up," she added.

A St. Louis County police officer was shot in the shoulder and a police officer from the St. Louis suburb of Webster Groves was shot in the face at around midnight local time (1 a.m. ET) outside Ferguson police headquarters, as protests began to wind down, police said.

Both officers were released from the hospital Thursday. St. Louis County Police Chief Jon Belmar said three or four shots were fired at a group of police from about 125 yards away. He called the shooting an "ambush" and said the officers are lucky to be alive.

Investigators on Thursday took several people in for questioning, but they were later released and no arrests have been made, said Sgt. Brian Schellman, a spokesman for St. Louis County police. St. Louis Regional Crimestoppers offered a $10,000 reward for information leading to the arrest of the shooter or shooters.

The St. Louis County Police Department and the state Highway Patrol took over command of protest security Thursday.

Several Ferguson officials, 

including the police chief

, Thomas Jackson, have resigned after a 

Department of Justice report

found a pattern of racial discrimination in the city's police and courts systems.

The shootings were condemned by the parents of Michael Brown, whose death at the hands of a Ferguson police officer in August touched off protests that continued Wednesday night after Jackson resigned. They called the shootings "senseless" and blasted what they called "stand-alone agitators" attempting to derail peaceful protests.

U.S. Attorney General Eric Holder called the shootings 

a "disgusting and cowardly attack"

 carried out by "a damn punk." President Barack Obama also condemned the violence, and said on Twitter that the "path to justice is one all of us must travel together."

St. Louis County police and the Missouri Highway Patrol will be providing security, but regular policing will continue to be conducted by the Ferguson Police Department, authorities said. Ferguson police had been in charge of security after a state of emergency ordered by Gov. Jay Nixon expired in December. The St. Louis County Police Department was criticized for using military-style equipment and tear gas on protesters in the first days of protests after Brown, 18, who was unarmed, was killed on Aug. 9.

Ferguson Mayor James Knowles III called for calm. "While we respect the right to peacefully protest, we cannot continue to move forward under threats of violence and destruction to our community," the city said in a statement Thursday.