A Brussels Airlines plane heading to the Portuguese city of Faro took off from Brussels Airport on Sunday, the first passenger flight to leave the airport since suicide bombings on March 22 ripped through its check-in counters.

Security at the airport was tight with completely new check-in procedures for passengers. Two other planes were scheduled to leave later Sunday -- Brussels Airlines flights to Athens and Turin, Italy -- from a European aviation hub that used to handle 600 flights a day.

Arnaud Feist, the CEO of Brussels Airport Co., called Sunday's flights a symbolic "sign of hope" following "the darkest days in the history of aviation in Belgium."

He also thanked all employees for their courage.

"We are more than an airport ... We are a family more bound together than ever," he said at an airport ceremony Sunday.

Damage to the airport was extensive when double suicide bombs exploded near its crowded check-in counters 12 days ago, killing 16 victims and maiming people from around the world. Another bombing that day on a Brussels subway train killed 16 other people. Both attacks were claimed by the Islamic State group.

Feist said Belgium's biggest airport should be back around 20 percent of capacity on Monday and able to process 800 passengers an hour. He said Saturday that he hoped full service at the airport could be restored by the end of June or the beginning of July in time for the summer vacation season.

New security measures at the airport aimed to minimize the chances of any repeat attacks.

Police on Sunday conducted spot checks of vehicles before they arrived. A large white tent was set up outside the terminal to screen travelers' IDs, travel documents and bags before they were allowed to enter the building.

A drop-off parking area outside the terminal was closed down and authorities said there would be no rail or public transport access to the airport for the foreseeable future.

The bombers entered the check-in area with suitcases packed with explosives and nails, and the resulting blasts collapsed the airport's ceiling and shattered windows.

The attacks have prompted a wider discussion among aviation authorities in many countries over whether to impose routine security checks at the entry to airport terminals