Street battles have been raging between security forces and armed gangs in the Venezuelan capital Caracas.
No official death toll has been given but local media reports say more than 10 people have been killed since the fighting began on Wednesday.
Hundreds of officers have been deployed to seize weapons and search for gang leaders, who have been seeking to expand their territory.
One local resident said the recent violence was "like a war".
Images shared on social media showed bullet castings littering the ground in the Cota 905 neighbourhood on Friday.
One officer told AFP news agency that authorities were now in control, but said "there may still be a few snipers".
Some 800 security personnel were deployed to affected areas, where they conducted house-to-house searches.
Interior Minister Carmen Meléndez said police had "advanced in the dismantling of the criminal structures that have settled in these territories with the intention of sowing terror".
She said the officers had freed citizens kidnapped by the gangs, and would remain deployed "as long as necessary".
The Venezuelan government has offered rewards of up to $500,000 (£360,000) for information leading to the detention of gang bosses.
The operation marks the first time in years that authorities have launched a major offensive against the gangs, AFP reports.
The government accuses the opposition, with the help of foreign powers, of orchestrating the violence to "destabilise" President Nicolás Maduro.
Local human rights groups called for a de-escalation in the violence, expressing "deep concern for the lives and safety" of local residents.
While the shooting appears to have died down, dozens of civilians have been fleeing their homes, frightened of being hit by bullets.
"We are experiencing trauma", one Cota 905 resident told the Associated Press news agency.
