Venezuelan police clashed with a group of soldiers in the capital, Caracas, late last night in the latest incident between rival armed forces.
Gunfire erupted in the centre of the city when about 40 military police officers briefly overran as police station and tried to force out a commander who a day earlier had arrested an army lieutenant.
There were no immediate reports of injuries although four military officers were arrested, officials said. Local television showed images of an armored police van pockmarked with bullet holes.
Venezuela, the world's fifth largest oil exporter, has been rocked by political conflict for more than a year between left-wing President Hugo Chavez and opponents who accuse him of assuming dictatorial power.
The clash came seven months after Mr Chavez ordered the military to temporarily take over the metropolitan police run by anti-Chavez mayor Mr Alfredo Pena.
Mr Chavez, a former paratrooper who survived a coup in April last year, accuses his foes of using the police as a hostile paramilitary force.
He recently threatened to take over control of the 9,000-strong autonomous metropolitan force for the second time after they clashed with his radical supporters during a violent street protest.
Several rival police forces in the capital are run by municipal mayors - both supporters and opponents of the president.