A violent explosion in the port area of the Lebanese capital, Beirut, left at least 50 dead and more than 2,500 injured.
The explosion was so powerful that it caused damage to streets and buildings for miles across the city.
The cause is not yet known, the interior minister said preliminary information points to highly explosive products which had been seized years ago and stored in the port.
Prime Minister Hassan Diab has said those responsible will be severely punished.
Videos of the explosion scene in the port area show smoke rising from a first explosion, then a much larger explosion that appears to have engulfed several neighboring buildings.
A witness told the BBC the explosion was so large he thought he was going to die.
Hospitals would be overwhelmed with wounded; firefighters tackle many fires.