Dramatic photos of black smoke billowing from the tank were shared on social media, including some by Labour MPs Poto Williams and Louisa Wall who were in Apia for a UNDP meeting at the New Zealand High Commission.
Ms Wall said police were redirecting traffic away from the direction of the fire, and she had been about 1km from the wharf when she saw the billowing smoke coming from the tank, followed by orange flames.
"We were having a meeting in the board room, and then someone said 'oh my gosh, can you see the smoke?' People were getting up on their chairs to get a better view."
She said within a few minutes of the fire breaking out the group was evacuated
Samoa born Labour MP Su'a William Sio said he was in contact with friends in Apia yesterday, when the fire broke out.
"It seems police and the fire service have cordoned off the area and are trying to stop the fire from spreading to the other two tanks," he said.
"It's concerning because that whole area is quite busy with several restaurants, clubs and about four accommodation areas, plus shipping and customs offices with several hundred staff."
Mr Sio said the port was also used by cargo and cruise ships, fishing boats and ferries to Tuvalu and American Samoa.
Samoa's Disaster Management Office (DMO) reported that the fire was fully extinguished by 3.15pm.
Yesterday the office warned people to stay away from the area.
"We advise the public to refrain from going towards the Matautu area due to an incident where one of the fuel tanks has caught fire. Current situation is unstable and unsafe for the travelling public. Please be vigilant," the organisation wrote on its Facebook page.
The Samoa Observer reported that part of efforts to fight the fire included attempts to remove fuel from the other two tanks.
"Fuel tanks have been running back and forth as part of the operation."
