PORT-AU-PRINCE, Haiti (AP) — 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.

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.

It wasn’t immediately clear as of late Monday whether the attack, which was the biggest one in Haiti’s history involving the airport, was successful.

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.