SINGAPORE - Fire and rescue specialist Muhammad Hud Ayub was in the middle of his routine physical training in Telok Blangah on March 20 when a call came in.

The full-time national serviceman was to report to Pasir Panjang Ferry Terminal with his team as quickly as possible to help put out a blaze at an island south of the mainland.

"I felt an adrenaline rush," said the 19-year-old. "I immediately went into action, preparing for what I need."

Mr Muhammad was one of 128 Singapore Civil Defence Force (SCDF) personnel deployed to fight an oil storage tank fire on Pulau Busing, an island south-west of Singapore. When he got off the barge, he saw thick columns of smoke rising to the sky. "I felt the radiant heat when I got nearer to the site," he said.

For 10 hours, Mr Muhammad carried out duties like adjusting ground monitors and replacing hoses. The fire took six hours to put out, with operations ending around midnight.

The force deployed 31 firefighting and support vehicles, including a large gun which can shoot 6,000 gallons of water a minute. The firefighters were later praised by Prime Minister Lee Hsien Loong and Home Affairs Minister K. Shanmugam.

Colonel Alan Chow, who heads SCDF's first division, said his team was "quite composed" when the call came in. His first concern was whether there were casualties as information on the fire was scant at that time.

"We needed to know if there were people injured or trapped," he said. Luckily, nobody was trapped or injured.

Another concern was speed. Col Chow noted that the logistic requirements make an offshore fire harder to deal with.

For the fire on Pulau Busing, officers had to arrange for a barge to move their firefighting equipment and support vehicles. One of two large water guns housed on Jurong Island was moved to Pulau Busing in a barge via Pasir Panjang Ferry Terminal.

A water gun needs to be connected to a pump, hose laying truck and foam pod. Foam helps to blanket fires, depriving them of oxygen while a pump regulates the intensity of the spray. A hose laying truck acts like an extension cord, connecting to a fire hydrant.

Making sure that the set-up does not obstruct traffic is a priority for first responders.

Nearby oil storage tanks were another concern. First responders use thermal imagers to make sure temperatures were kept under control "for exposure protection", though at the time of the fire, their temperatures were "very high", said Col Chow.

The next step was to put out the fire and ensure it did not rekindle. The best way was to transfer the contents of the fire out, an effort that lasted for a couple of days.

In its updates on the Pulau Busing fire, the SCDF posted Facebook photos of exhausted firefighters resting on the road, soaked in a mix of water and perspiration. One was of a fireman pouring water on his head to cool off.

Oil tank fires are rare in Singapore. "Some officers got through their careers not having fought one," said Col Chow, noting that the last oil tank fire was on Jurong Island in April 2016. The large scale of the fire also warranted the SCDF's deployment of the large gun and other resources, he added.

"We also had to make sure that there was sufficient coverage for fires on the mainland, such as Housing Board fires, in case they happen," Col Chow said.

Mr Muhammad, who stayed on Pulau Busing until 4am, said: "I wanted the fire to be quickly put out. I felt relieved that the fire was under control and nobody was injured... I was drenched in sweat head to toe afterwards."