The content of the tanker flowed through a gutter into a canal about six poles away from the scene of the incident, which occurred around 11am near the Mummy B junction.
The affected family members were said to be asleep in their house located close to the canal, when the inferno started.
It was learnt that the deceased were burnt beyond recognition, while two others were rescued by neighbours.
It was gathered that the tanker later went up in smoke four hours after it had fallen into the gutter.
The victims, a mother and two of her children, who were only identified by eyewitnesses as Wisdom, Esther and Blessing Lebara, used to sell banana at the Waterlines in Port Harcourt.
The fire reportedly razed properties worth several millions of naira.
An eyewitness, who identified himself as Pastor Sunday Etienam, told Southern City News that he helped to save the two surviving siblings, while lamenting the death of their single mother and two of her children.
He said, “My house was also burnt; I helped to save Joseph and Miracle from the house after I heard them crying, otherwise it would have been five casualties today.
“Their house was affected first because they were closer to the canal, before the fire spread to my house and others. It is shocking to us.”
Another neighbour, Chinedu Ukaro, said he lost everything to the inferno after he managed to escape into a nearby bush.
He stated, “I managed to carry my children into the nearby bush; we lost everything to the fire, even the clothes I am putting on now, someone gave them to me.
“We heard that the fire was caused by a fallen tanker; let the government do something about these tankers in Nigeria.”
An eyewitness living around Rumuola told our correspondent that the tanker crashed into a big gutter in Rumuola, along the Aba Road around 11pm on Monday, but caught fire around 3am the following day.
He said, “The tanker that was carrying petrol fell around 11pm on Monday and emptied its content into the gutter, but the fire started around 3am on Tuesday.
“By the time the fire started, the tanker was already empty, so there was no much fire and impact around here except for the drainages that were damaged.
“The driver escaped with the head of the tanker, but he was apprehended around Timisoara.”
Another eyewitness, who asked not to be named, said the fire started from the canal, adding that it trailed the fuel flow line from the gutter back to the tanker. SHARE THIS STORY USING ANY OF THE BUTTON BELOW ⬇ PLACE YOUR TEXT ADVERT BELOW ⬇⬇⬇