Four Los Angeles police officers were acquitted of assault today in the videotaped beating of a black motorist that stunned the nation. The verdicts immediately touched off a storm of anger and scattered violence in the city.

As residents set scores of fires, looted stores and beat passing motorists in the downtown area and pockets of predominantly black south-central Los Angeles, Mayor Tom Bradley declared a state of emergency, and Gov. Pete Wilson said he would send in the National Guard.

After hearing seven weeks of detailed testimony and studying the 81-second amateur videotape of the beating, the jury concluded that the policemen, all of whom are white, had not broken any laws when they clubbed and kicked the mostly prone motorist, Rodney G. King.

It was deadlocked on one of the 11 charges, and the prosecution said it might seek a new trial on that charge, which affected only one defendant.

The beating last spring, with its kicks and its 56 baton swings, was shown over and over on television. It immediately became one of the most visible uses of force by police in this country's history and put the issue of police brutality on the national agenda.

Immediately after the verdicts, an unusually impassioned Mayor Bradley appeared on television to appeal for calm in a city where the videotape has come to symbolize complaints about police brutality, racism and street violence.