A bomb exploded at a Venezuelan television station critical of President Hugo Chavez's government, destroying three vehicles but causing no injuries, authorities said Monday.

The attack on Globovision late Sunday raised fears of increasing lawlessness in Caracas, Venezuela's capital, after President Hugo Chavez ordered an army takeover of the city police force.

National Guard armored personnel carriers and heavily armed troops blocked access to police stations Monday. On Sunday, guardsmen fired tear gas and rubber bullets to break up an opposition protest outside the Mariperez precinct, where officers resisted the federal takeover.

Elsewhere, hundreds of civilian protesters parked their cars to block a highway outside Caracas' air force base Monday. They honked car horns and waved red, yellow and blue Venezuelan flags.

The bombing at Globovision "was meant to frighten us. But neither bombs nor bullets are going to stop us from reporting the truth about the mistakes and excesses of this government," said station director Alberto Federico Ravell.

The attack occurred hours after Globovision broadcast footage of a pro-Chavez street activist applauding and embracing the guardsmen who fired on opposition protesters Sunday, Ravell said. The station received several telephone threats before the bombing, he said.

It was the latest attack against institutions and people perceived as Chavez opponents. Grenades and crude bombs have exploded outside news media outlets, the offices of Venezuela's largest labor and business federations and the home of the archbishop of Caracas.

There have been no arrests.

Chavez has dangerously divided the military, dragged the nation into recession, and polarized the country over his rule. Opponents want a nonbinding referendum on his rule, hoping to persuade him to step down.

On Sunday, billowing tear gas engulfed the Mariperez police precinct after protesters attempted to push their way through a security checkpoint outside the station. Four protesters were detained.

Hundreds of pot-banging protesters gathered outside the station, home of an elite motorcycle unit, and shouted "Get Out! Get Out!" and "Coup Plotters!" at the soldiers.

Officers at the Mariperez precinct — one of 10 in the city — refused to accept the takeover by federal forces, and control of police across the city remained in question.

The government took command of the 9,000-strong force Saturday to end a six-week labor dispute between officers loyal to the president and others who side with Caracas Mayor Alfredo Pena, a Chavez opponent.

Police Chief Henry Vivas, appointed by Pena, refused to step down, even after Interior Minister Diosdado Cabello named Gonzalo Sanchez Delgado as the new chief.

Chavez said the government ordered the takeover because disputes within the force "had become unbearable."

"We have to impose authority," Chavez said during his weekly radio program.

Pena accused Chavez of trying to create chaos so he can justify declaring martial law. Chavez accuses Pena and the opposition of seeking a coup.

Also Monday, a blast at a fireworks stand killed three and injured six during morning rush hour in downtown Caracas, the fire department said. Fire officials were investigating, and the explosion was not immediately linked to political dissent.