The mayor of Cincinnati, Ohio, declared a state of emergency Thursday morning after three nights of protests against the police shooting of an unarmed black man. Mayor Charles Lukens also announced a citywide curfew; only people going to and from work will be allowed on the streets between 8 p.m. and 6 a.m. Officials have considered calling out the Ohio National Guard, but no decision has been made yet.

The fatal shooting occurred early Saturday morning when a Cincinnati policeman, Steven Roach, chased 19-year-old Timothy Thomas into an alley and shot him in the chest at close range. The cop pursued Thomas because he fit the description of an individual sought by the police for 14 warrants, all of them misdemeanors or traffic violations. Thomas was the father of a three-month-old son.

Police spokesmen say Roach believed Thomas was reaching for a gun, an extremely unlikely action for a cornered, unarmed man confronted by a policeman at two in the morning. Even the mayor has admitted that the cop's story is improbable. Lukens told reporters Tuesday that top-level police officials were privately expressing doubts. “I have been told they are troubled by the story they are getting,” he commented. “The initial findings don't back him up.”

Violence erupted Monday evening following a police news conference and an afternoon meeting of angry residents and City Council members at City Hall. According to press accounts, protesters screamed at Council members and prevented them from leaving during a three-hour confrontation.

Thomas's mother, Angela Leisure, took the podium at one point and demanded an explanation for the shooting of her son. “You took him from his family and his son, and we want to know why. And don't get me wrong, even when you tell me why, it's not going to make it better.”

Monday night hundreds of angry protesters assembled outside police headquarters to express their anger over the police killing. Police in riot gear sprayed the crowed with a chemical irritant and fired at the protesters with beanbag guns. A brick was thrown through the glass front door. Ten arrests were reported.

The rioting became more serious Tuesday afternoon and evening as crowds, mostly black youths, took to the streets. In the downtown, Over the Rhine, and West End areas of Cincinnati, crowds broke windows and knocked over garbage cans, vendors' carts and statues. Numerous stores were broken into and looted. Police, some walking arm-in-arm and others riding horseback down the city's streets, used tear gas and guns loaded with rubber bullets and bean bags.

Several white motorists were reportedly dragged from their cars and beaten, although in some cases the victims of these attacks were defended by black residents. Sixty-six people were arrested, including five juveniles.

The violence continued on Wednesday night, although reduced to scattered incidents. Another 82 people, including 22 juveniles, were arrested, as police cracked down. A policeman was hit by a bullet Wednesday night but escaped injury because he was wearing a protective vest. Early Thursday morning residents broke into clothing and furniture stores, and fires continued to burn in several Cincinnati neighborhoods.

In announcing the state of emergency, Mayor Lukens said, “Gunfire went off [last night] that you might hear in Beirut or some other place. It is dangerous and getting more dangerous...”

The shooting of Timothy Thomas was the most recent in a series of incidents involving police abuse in Cincinnati. The city's police force has a long history of racism and violence:

* Thomas was the fourth black man killed by Cincinnati police since November, and the fifteenth such victim since 1995. On November 7, 2000, Roger Owensby, 29, was killed while in police custody. He was approached by police in a convenience store, and when he tried to flee he was tackled, sprayed with a chemical irritant and handcuffed. He died from asphyxiation, either by strangulation or a “piling-on” situation in which the victim's chest was compressed. The following day, Jeffrey Irons, 30, was shot dead by police after allegedly trying to steal deodorant and soap from a grocery store. The US Justice Department announced its intention to conduct an investigation into the two deaths.

* In March of 2000 Cincinnati City Council passed a resolution outlawing the practice of racial profiling, in response to public outrage.

* Cincinnati Police Chief Thomas Streicher used a racial epithet during a May 2000 training session and was forced to agree to counseling as a result. In June 2000 a federal mediator was brought in to help ease racial tensions between the police and the city's blacks, who comprise some 40 percent of the 331,000 residents.

* Last November a citizens' review board criticized the police over the 1998 killing of Thomas Blair. The review board said the city's investigations into the shooting were so poorly done that it could not determine whether the shooting was justified.

* The American Civil Liberties Union and the Cincinnati Black United Front filed a law suit in March of this year accusing the police department of illegally targeting and harassing blacks on the basis of their race for the past 30 years.

The killing of Timothy Thomas is only the latest in a string of police crimes in the US against working class victims, for the most part blacks or other minorities. Among the most well-known cases are the murder of African immigrant Amadou Diallo in a hail of bullets in February 1999 and the torture of Haitian-born Abner Louima in August 1997, both in New York City. In Los Angeles investigations revealed a widespread pattern of unjustified arrests, beatings, witness intimidation, illegal shootings, planting of evidence, frame-ups and perjury by police in the CRASH unit of the Rampart Division.

According to recent press reports, the Detroit police force has been carrying out mass arrests in homicide cases in order to coerce witnesses into talking. In 1998 Detroit police arrested 1,310 people while investigating 430 murders, an unheard of ratio. A federal lawsuit was filed in March in Detroit seeking to ban the “pattern and practice of arresting witnesses who may have knowledge of murders but who are not involved in the actual murders.”

Revelations of systematic police violence and corruption have emerged in a whole number of major US cities over the past decade, and police killings of minority workers or youth occur with almost mind-numbing frequency.

The rioting in Cincinnati reveals the enormous social tensions lying just beneath the surface of American society. Social conditions are similar in every major urban area. On the one hand, a small minority has prospered and enjoys fabulous wealth; on the other, a considerable section of the population lives in poverty or just manages to stay above the poverty level. The police violence and murders are themselves a function of social inequality, as the worsening conditions make further repression by the authorities inevitable. The events in Cincinnati, coming as they do at the onset of a sharp economic downturn, could herald social eruptions in other US cities this spring and summer.