Backers of leftist Bolivian President Evo Morales set fire to a state capitol Monday in a protest to demand the resignation of a governor allied with the conservative opposition.

The thousands of protesters, including Indian groups, labor unions and coca farmers, also vowed in television interviews to begin a blockade Tuesday morning of highways leading into Cochabamba, 140 miles southeast of La Paz.

On Monday, the protesters set fire to the heavy wooden doors of the state's historic capitol and took control of its first floor offices as the blaze spread, charring furniture and destroying some government records. They also set fire to two cars parked on the plaza outside. The images were broadcast on Bolivian television.

Earlier Monday, state police tried to dislodge the protesters from the plaza by firing tear gas grenades into the crowd. Protesters responded by throwing rocks.

Local media reported at least 22 were injured in the clash, several of whom were journalists covering the event.

Morales' administration immediately deemed the response excessive, firing the newly appointed state police commander two hours after he had assumed the post.

Government Minister Alicia Munoz, whose office oversees law enforcement throughout Bolivia's nine states, said the violence was an indication that the central government must keep tighter reins on local police.

"From this moment on, there will be control," Munoz said in a radio interview. "There will be control because we will not permit any more acts of violence or acts of repression against the social sectors who, in this case, were demonstrating peacefully."

It was the third time in recent weeks that demonstrators have packed Cochabamba's tree-lined central plaza to demand the resignation of state Gov. Manfred Reyes Villa, a former presidential candidate still widely considered to harbor national political ambitions.

Last month, Reyes publicly denounced Morales' handling of an assembly rewriting Bolivia's constitution, siding with opposition leaders who say each of the new charter's articles should be written by two-thirds of the assembly's delegates.

Morales, whose Movement Toward Socialism party, or MAS, holds just over half of the assembly's seats, says the charter should be written by a simple majority, with only a final draft facing a two-thirds vote.

In December, Reyes also called for Cochabamba to hold a second vote on a referendum to give Bolivia's nine states greater autonomy from Morales' central government.

The referendum was defeated in a nationwide election in July but the autonomy issue still divides Bolivia. Cochabamba, in the Andean foothills at the center of the country, joined four western highland states in rejecting the measure, while Bolivia's four eastern lowland states favored it.