Heavily armed gangs tried to seize control of Haiti’s main international airport on Monday, exchanging gunfire with police and soldiers in the latest attack on key government sites in an explosion of violence that includes a mass escape from the country’s two biggest prisons. Hours after the airport assault, officials said Haiti’s police academy came under attack by an armed gang.

The Toussaint Louverture International Airport was closed when the attack occurred, with no planes operating and no passengers on site. Associated Press journalists saw an armored truck on the tarmac shooting at gangs to try and prevent them from entering airport grounds as scores of employees and other workers fled from whizzing bullets.

The attack on the police academy, where more than 800 cadets are training, was repelled Tuesday after the arrival of reinforcements, said Lionel Lazarre of the Haitian police union.

Last week, the airport was struck briefly by bullets amid ongoing gang attacks, but gangs did not enter the airport nor seize control of it.

The attack occurred just hours after authorities in Haiti ordered a nighttime curfew following violence in which armed gang members overran the two biggest prisons and freed thousands of inmates over the weekend.

“The secretary-general is deeply concerned by the rapidly deteriorating security situation in Port-au-Prince, where armed gangs have intensified their attacks on critical infrastructure over the weekend,” said U.N. spokesman Stephane Dujarric.