DUBAI: Dubai authorities were Thursday investigating an explosion on a container ship carrying flammable materials, which unleashed a fireball at one of the world's busiest ports and sent shock waves through the city.

Firefighters rushed to the scene at Jebel Ali Port to tackle the blaze that broke out on a large vessel stacked with containers which authorities said had been preparing to dock.

Flames and smoke poured from the ship but authorities said it was doused within 40 minutes and that there were no casualties, with all 14 crew members evacuated in time before the explosion.

"Thank God, everything is safe. But this is a natural accident that happened in one of the containers, which was also carrying some flammable materials. There was no other reason," Mona Al Marri, director of the Dubai Media Office, told Al-Arabiya television.

She said there will be an investigation into the cause of the blast. Police vehicles and fire trucks were Thursday still parked close to the heavily damaged vessel, with burned containers visible on the quayside.

Residents of apartment towers and villas that line the city's coast reported hearing a loud bang in the night and then felt windows and doors shaking after the fireball shot into the sky, with some filming the spectacle from their balconies.