Authorities in Dubai were investigating on Thursday an explosion on a container ship that rocked a Dubai port and sent shock waves through the city, reported news agency AFP. Firefighters poured cascades of water on the ship. The blaze was doused within 40 minutes, the ship authorities said, as per AP reports.

Here is what we know so far about the blast:

Where did the blast occur?

An explosion occurred on Wednesday at a container vessel that was docked at Dubai's Jebel Ali Port. The police said three of the 130 containers on the ship held flammable materials.

Also read: Iran explosives factory blast injures 9: Report

What was the reason behind the blast?

As of Thursday, the Dubai authorities are investigating the explosion. 

"This is a natural accident," Mona Al Marri, director of the Dubai Media Office, told Al-Arabiya television.

It "happened in one of the containers, which was also carrying some flammable materials. There was no other reason," she added.

Mona Al Marri, however, said there will be a probe into the blast.

Was there any casualty?

Ship authorities said that the fire was doused within 40 minutes and there was no casualty, the news agency reported. All 14 crew members evacuated in time before the explosion, they said.

Is Jebel Ali Port unsafe?

Such events are rare in Dubai. 

Meanwhile, Jebel Ali port is capable of handling aircraft carriers. It was the US Navy's busiest port of call outside of the United States in 2017.

Also read: Gas blast in China's Hubei province kills 12: Officials

Jebel Ali Free Zone 

Located in the Jebel Ali area at the far western end of Dubai, Jebel Ali Free Zone (JAFZA) houses 8,000 companies that contributed 23% of Dubai's gross domestic product last year.

It is the largest trade zone in the middle-east.