Gangs of black youths hurled rocks, smashed windows and set fire to four buildings last night, launching a second round of violence in the predominately black southwest section of this central Florida city.

At least four people, including a television reporter, were injured as gangs of black youths roamed the area, tossing rocks and breaking into stores. The reporter was kicked and beaten and the other three people were treated for minor injuries, officials said.

Heavily armed officers in riot gear swept through the area, clearing people from the streets and making numerous arrests.

Police closed off 16 square blocks and called for reinforcements from sheriff's deputies and highway patrol troopers.

About 100 police officers had been ordered on alert earlier in the day, after rock and bottle throwing broke out shortly after midnight Tuesday, triggered by the arrest of a black woman at a cafe.

A 14-man SWAT team and four local ministers had succeeded in calming tempers by daybreak yesterday. Two policemen were slightly injured by flying debris and five people arrested in the first outbreak of violence yesterday morning.

At a midday meeting between officials and blacks, a city commissioner promised -- amid hoots and insults -- that police behavior would be investigated.

Mayor Carl Langford, who didn't attend yesterday's meeting, said, "our last class of police recruits was over 60 percent black and Hispanic, but they don't want that. They want high positions immediately."