At least 1,500 inmates fled from a prison in Maputo, amid ongoing unrest over the declaration of the long-ruling Frelimo party as the winner of the recent elections.
A total of 1,534 detainees escaped the high-security prison located about 15 kilometers (nine miles) from the capital, said national police chief Bernardino Rafael at a news conference.
Among those attempting to escape, 33 were killed and 15 wounded in clashes with prison staff, he added.
A search operation, backed by the army, led to the arrest of about 150 fugitives, he said.
Around 30 of the prisoners were linked to armed groups that have been behind unrest and attacks in the northern province of Cabo Delgado for the past seven years.
"We are particularly concerned about this situation," Rafael said.
The Portuguese-speaking African country's highest court had confirmed on Monday that Frelimo, in power since 1975, won the Oc. 9 presidential election that had already triggered weeks of unrest.
Groups of protesters had approached the penitentiary Wednesday, creating confusion and triggering unrest inside the prison, where inmates ended up knocking down a wall through which they escaped, he explained.
Barricades remained erected in several areas of the capital Wednesday, limiting movements, as acts of vandalism continued.
In addition to stores and public buildings that were already ransacked Monday, ambulances were set ablaze along with a drugstore and other businesses, according to an AFP correspondent.
Some demonstrators also set up tables in the streets to occupy the space while celebrating Christmas with family or neighbors, an AFP journalist witnessed in several working-class districts of Maputo.
Monday's confirmation of the election result came despite claims of irregularities from many observers.
Frelimo leader Daniel Chapo won 65.17% of the vote, about five points less than the initial results declared by the country's electoral commission.
Chapo's main challenger, exiled opposition leader Venancio Mondlane, has claimed the election was rigged, sparking fears of violence between rival party supporters.
The unrest has claimed the lives of at least 150 people, according to several NGO reports.
