Explosion heard at Brussels airport, evacuation underway

An explosion has been heard at Zaventem Brussels airport, Sky News reports, with reasons still unclear. Airport is being evacuated now after several people injured, Belgian media says.

Sky's Alex Rossi, at the scene, said: "I was in the duty free in Zaventem Airport and I heard two very, very loud explosions. I could feel the building move. There was also dust and smoke as well."

Rail traffic to airport has been suspended, and airport now on lockdown, sources report.