More than 1,500 inmates have escaped from a prison in Mozambique, taking advantage of ongoing political unrest over disputed election results, police said.

Police Chief Bernardino Rafael told a news conference that 33 people were killed and 15 injured in clashes with guards.

He added that some 150 more fugitives have since been captured.

Protests erupted on Monday after Mozambique’s Supreme Court confirmed the victory of October’s presidential election by the Frelimo party, which has ruled since 1975.

Rafael said a group of anti-government protesters approached a prison in the capital Maputo on Wednesday. Inmates took advantage of the commotion to knock down walls and escape, he said.

Mozambique has been in turmoil since a disputed election in October. Official results showed Daniel Chapo, the ruling Frelimo presidential candidate, the winner.

Fresh protests erupted on Monday after the Constitutional Court ruled that El Chapo had won the election while downgrading his margin of victory.

Preliminary results in October showed Daniel Chapo receiving 71% of the vote, while his main rival Venâncio Mondlane received 20%. The court has now ruled that he won 65% and Mondelein 24%.

one BBC reporter discovered Maputo resembled a ghost town on Christmas Eve, with almost all businesses closed and people staying home to avoid falling into the city’s worst riots since Frelimo came to power in 1975.

Frelimo offices, police stations, banks and factories across the country were looted, vandalized and set on fire. The interior minister said late Tuesday that at least 21 people had been killed in unrest since Monday.

Mondlane, who fled Mozambique, has been calling on his supporters to demonstrate against what he says was a fraudulent vote.

He said in a social media message over the weekend that there could be a “new popular uprising” if the results were not overturned.

Three months of protests since the election have left about 150 people dead.