At least one person has died and two others are still missing after an oil and chemical tanker caught fire off the coast of Lamma Island in Hong Kong on Tuesday.

Authorities said the blaze, which began at around 11.30am and was finally put out at 4.30pm, is believed to have started when the Aulac Fortune, a Vietnamese-registered vessel, was in the process of being refuelled by an oil barge.

One crewmember dead, two still missing after huge explosion on chemical tanker Aulac Fortune off Lamma Island, Hong Kong

“Before refuelling there were three reports of explosions before the oil tanker burst into flames,” a source said.

Three helicopters have been sent to the scene and are still searching for the missing sailors, while three fireboats, and marine police vessels were also sent to the area.

Emergency personnel rescued 23 sailors, who had either fallen or jumped into the sea to escape the blaze. Four who had been injured in the explosion were taken to Queen Mary Hospital in Pok Fu Lam, and Ruttonjee Hospital in Wan Chai for medical treatment.

One sailor is in a serious condition suffering from burns, and another, a 46-year-old Singaporean man, had shoulder wounds.

Officials said there were 25 crew members on board the 17,000-tonnes tanker, while one of the injured had been part of the Singaporean crew on the oil barge.

Initial reports suggest the incident occurred as the two ships were in the process of connecting fuel hoses, a source said.

The source said the oil barge was able to leave the scene, and the cause of the explosion was being investigated.

During the height of the fire, pictures showed large clouds of black smoke billowing out of the tanker, which has a huge hole in its bow and is listing heavily to starboard.

The oil and chemical tanker, which comes under the smallest classification for that type of craft, caught fire about one nautical mile south of Lamma Island soon after 11.30am, according to police.

Yip Tsz Leung, deputy director of the CY Tung International Centre for Maritime Studies said the area was a common spot for ships to stop offshore to take on fuel, a process he said was “quite a dangerous moment”.

One of the sailors who was sent to hospital said the incident occurred while he was resting.

“I was sleeping, I don’t know what happened,” he said, adding that he felt OK and wanted to know details about his colleague.

Vietnamese consul Nguyen Van Phong arrived at Ruttonjee Hospital at 3.30pm to visit the injured.

The Aulac Fortune had unloaded petrol it was carrying in Dongguan, Guangdong province on Sunday and arrived in Hong Kong at 5am on Tuesday.

Residents as far away as Discovery Bay and Mui Wo on Lantau Island reported hearing a loud boom and windows shaking.

“I thought it was an earthquake when the windows started to shake,” Mui Wo resident Rhea Nee, 42, said.

“We usually have strong winds ... but when I looked outside, the trees were perfectly still.”

Some shaken residents left their homes and gathered outside.

“I was waiting for the tremors and they didn’t come,” Nee said. “I ran out barefoot as I was folding my kids’ clothes. I ended up outside holding a stack of clothes.

“The windows shook violently. Like when there is a [typhoon signal No 10].”

Source: SCMP