Two people were killed at Moldova's main international airport on Friday when a "foreign citizen" who was not allowed to enter the country opened fire, according to the country's Interior Ministry.

"Tragic day for Moldova after the incident at Chisinau International Airport, resulting in two lives lost," Moldova's Deputy Prime Minister and Minister of Foreign Affairs Nicu Popescu said in a Twitter post Friday.

"My heartfelt condolences to the bereaved families. We've mobilized all forces to ensure passengers' safety," Popescu said, adding "flights will be resumed soon."

The Interior Ministry said in a statement that a foreign national who was not allowed to enter Moldova had killed the two victims with a firearm. The attacker was injured and is receiving medical care, the ministry said.

All relevant state authorities are on the scene and "efforts are underway to bring the situation back to normal," the ministry added.

The General Prosecutor's Office is opening a criminal investigation into the incident.

"The leadership of the country has been urgently informed of the situation," the ministry added.

A witness on the scene told CNN passengers at the airport were evacuated from the main building and that afterwards they heard several shots.

"At the moment, commercial activity and flight schedules continue to be disrupted," the ministry said.