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HONG KONG — An oil tanker exploded off Hong Kong's southern coast Tuesday, killing one crew member and leaving three others missing at sea.

Witnesses reported hearing a loud blast that shook windows several miles away.

The damaged oil tanker tilts to one side off Hong Kong's southern coast. Anthony Wallace / AFP - Getty Images

Authorities said the Vietnam-registered vessel burst into flames as it prepared to refuel.

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Twenty-one crew members were rescued from the waters.

The Aulac Fortune was built in 2010. Ship tracking data shows it last loaded around 6,660 tons of gasoline, most of which was delivered to Guangzhou on Sunday and Monday.

The Aulac Fortune later arrived south of Lamma Island and sent its position from there at midnight ET on Tuesday.

The Aulac Fortune burns near Lamma Island on Tuesday. Hong Kong Government Flying Service / EPA

Residents on the nearby island of Lantau said they heard a big blast which rattled doors and windows.

"It felt like when there is a strong typhoon, when the wind shakes your doors violently. It was really strong," Rhea Nee told Reuters. "I thought maybe there was an earthquake. I saw my neighbors all coming out of their houses. The windows of my house were shaking."