SANTIAGO, Chile (AP) _ Protesters against the military government of Gen. Augusto Pinochet threw stones and firebombs at vehicles and battled police from behind barricades of burning tires. Police said four people were wounded and more than 100 others were arrested.

The capital city was blacked out late Tuesday by a bomb that destroyed a major electric transmision tower, the state electric company said. Power was being restored gradually.

Police said four people were injured by gunfire in several hours of street protests Tuesday, while news reports and Roman Catholic Church sources reported additional injuries but gave no figures. The sources said some people were hit by buckshot from police shotguns.

Four other people also were injured in 15 bomb explosions Monday night in Santiago and the port city of Valparaiso, 83 miles to the west, police reports said.

The demonstrations, which lasted well into Tuesday night, were organized by political parties and other groups opposed to Pinochet, who came to power in a September 1973 coup against the elected government of President Salvador Allende, a Marxist.

The protesters also called for the release of six dissident labor and community leaders who have been in jail for 40 days, charged with organizing an anti-government demonstration on Sept. 4. The six began a hunger strike Friday to protest their detention.

Police said the four people were shot in separate incidents in suburban working class districts of Santiago.

They said Fernando Urrejola, 17, was shot in the stomach near an intersection where demonstrators erected a barricade to stop traffic. They said he was in hospitalized in serious condition.

The other three - a 14-year-old boy, a 17-year-old girl and a 23-year-old man whose names were not given - were hit in the legs, apparently by stray bullets, according to police reports.

Police used tear gas and water cannons to scatter protesters. Some shops closed in downtown Santiago, but most stores and offices remained open and the protests did not seem to attract widespread public support.

Public transportation services were cut back, however, when demonstrators began throwing rocks at vehicles. Protesters also threw bent nails in the streets and flat tires idled many buses.

Police and students fought at three university campuses, and reports from the School of Medicine said one student was hit in the head by a tear gas grenade.

Demonstrators in slums on the city's outskirts set up barricades of burning tires and other debris to block streets. Witnesses said in at least one instance, soldiers fired their weapons into the air to scatter protesters.

The state electric company said a bomb destroyed an electrical transmission tower south of Santiago, knocking out power to the city of 5 million people and an area 55 miles around it.

An anonymous caller to The Associated Press claimed that a leftist guerrilla group, the Manuel Rodriguez Patriotic Front, had planted the bomb. There was no way to authenticate the call.

Soldiers patrolled many parts of Santiago and guarded power plants, communications centers and bridges.

Protests also occurred in Concepcion, 350 miles south of Santiago, and in Antofagasta, 920 miles to the north, police said. A radio station in Antofagasta said several demonstrators were injured by shotgun fire from police.

Late Monday an elderly Santiago woman and her granddaughter were injured by a bomb that exploded as they passed a power plant, police said. A bus driver in Santiago and a taxi driver in Valparaiso were injured when firebombs were tossed at their vehicles, police said.