Cincinnati police made at least 20 arrests Thursday night, enforcing a citywide curfew enacted as part of a state of emergency declared by the mayor as riots over the police shooting of an unarmed black man stretched into a fourth day. 

The 8 p.m. curfew dictated that only people going to and from work would be allowed on the streets between 8 p.m. and 6 a.m., Mayor Charles Luken said. 

Hundreds of police officers, some of them on horseback, patrolled the otherwise deserted streets at dusk, enforcing the citywide curfew.

"Basically, it's been relatively quiet," police Lt. Ray Ruberg said. "There's been fewer citizens on the street. It's looking better than it has, much better."

The mayor resorted to a curfew after four days of rioting that included motorists dragged from cars and beaten, fires set and one police officer shot. The officer's protective vest prevented injury.

"Despite the best efforts of the good citizens of our city, the violence on our streets is uncontrolled and it runs rampant," Luken said Thursday morning. "The time has come to deal with this seriously. The message is that the violence must stop."

Gov. Bob Taft ordered the State Highway Patrol to assist Cincinnati police, and the mayor said he may ask Taft to send in the National Guard.

As of Thursday, 86 people had been arrested in the looting, arson, vandalism, assaults and other violence in mostly black sections of Cincinnati.

The violence is Cincinnati's most sustained racial unrest since the rioting prompted by King's assassination.

Tensions exploded after Saturday's fatal shooting of Timothy Thomas, 19. Since 1995, 15 black men have died at the hands of Cincinnati police, four of them since November. No other people have been killed by police there since 1995.

Black activists said they had been warning city officials for two years that problems were coming because police were harassing blacks.

Kweisi Mfume, president of the National Association for the Advancement of Colored People, arrived Thursday to meet with Luken and tour areas of unrest.

More than 300 people packed a hot, spartan meeting room at a Baptist church in the Avondale neighborhood that was hit by violence overnight to hear Mfume appeal for calm and teamwork.

What started as a contentious meeting, with speakers attacking the NAACP for not doing enough, calmed down when Mfume urged them to channel their anger constructively.

"Everybody is angry. I'm angry, but anger has its place," he said. "It's got to be channeled, otherwise it's just frustration."

Later, as the crowd quieted and listened attentively, he said, "We want the world to see we are respectful in our anger. ... We don't want to burn down. We want to build up."

However, some of the young people in the audience rejected his call and urged more protests. They mocked the calls for peace and prayer.

Standing in the back of the room, 38-year-old William Harris, director of community service at the University of Cincinnati, listened to the young people, shook his head and said, "It ain't over. There's going to be a hot time tonight."

President Bush called Attorney General John Ashcroft to discuss ways the government can restore calm.

"The president understands the very strong emotions involved and he joins Cincinnati and Ohio leaders in their appeal to the people of Cincinnati for calm and a nonviolent resolution to the current situation," White House spokesman Ari Fleischer said.

Luken, a Democrat, acknowledged a "real problem with race relations" but said he had to separate that from the need to quell violence.

The curfew halted nighttime taxi service and forced cancellation of some Easter weekend events, including a Good Friday tradition in which Roman Catholics climb the hillside steps of Immaculata Church after midnight and pause on each step to pray.

The American Civil Liberties Union, which sued last month to accuse Cincinnati police of 30 years of illegally targeting blacks on the basis of their race, expressed concern about the indefinite curfew.

"Such drastic restraints on the freedom of the people are tolerable only as long as absolutely necessary to maintain public safety," the ACLU's Ohio chapter said in a statement.

"We don't like the fact that we have to declare a curfew," Luken said. "For 99.9 percent of the citizens of our city, a curfew is completely unnecessary. We ask our citizens to bear with us."

The curfew came too late for Brian Edmondson, manager of a clothing store. He swept out broken glass and took stock of what merchandise remained after the place was looted Thursday. The store's front was boarded up because the windows and door were smashed.

"I'm still pretty upset about it," Edmondson said.

On Wednesday, rioters broke windows, looted stores and assaulted at least one white motorist, who was dragged from her car. Others in the neighborhood came to the woman's aid. A police officer was shot, but his gunbelt buckle caught the bullet and he suffered only cuts and a bruise, the mayor said. No arrest was made in the shooting.

The unrest began in Over-the-Rhine, the poor, mostly black section where Thomas lived, and spread to several other largely black neighborhoods.

Thomas was killed as he fled Stephen Roach, an officer trying to arrest him for failing to appear for misdemeanor charges and traffic violations. Roach, 27, has been placed on leave. Roach has not commented, but his union said he feared for his life during the encounter.

Hamilton County Prosecutor Michael Allen said he will probably present the case to a grand jury next week. The U.S. Justice Department and the U.S. attorney's office in Cincinnati on Wednesday joined the FBI in a civil rights investigation.

-- The Associated Press contributed to this report