Up to 500 people were burned alive on Tuesday when fuel from a vandalized pipeline exploded in Nigeria's largest city, Lagos, emergency workers said.

Hundreds of residents of the Abule Egba district went to scoop fuel using plastic containers after thieves punctured the underground pipeline overnight to siphon fuel into a road tanker, locals said.

Abiodun Orebiyi, secretary-general of the Nigerian Red Cross, said there was no official death toll but estimated that between 200 and 500 people could have been killed.

"We know it is over 200 (dead). We are talking hundreds. We don't know if it is 300, 400 or 500," he said, adding that 60 people had been evacuated to hospital with serious burns.

This Reuters witness saw the remains of hundreds of bodies, most burned beyond recognition, lying at the scene of the explosion as emergency workers tried to put out the fire.

Some corpses lay rigid on the ground -- arms and legs in the air as if still trying to escape -- their clothes and skin burned off by the blast.

"A lot of people have been roasted. They are littered on the ground," a rescue worker said.