A FIRE engulfed the old Tilbury leisure centre on Saturday causing surrounding homes to be evacuated.
Six fire engines were sent to the building, in Civic Square, around 4.46pm, where thick clouds of toxic smoke were billowing out into the night sky.
It was initially feared that a homeless man had been camping inside, so fire crews had to search the building.
Up to 15 families in London Road were asked to leave their homes at about 5pm because of the health risks caused by the smoke.
There were also roadblocks in Civic Square and London Road.
But luckily no one was inside the two storey building and no one was injured.
Residents said there had been several fires in the empty building, but this was the first time they had been evacuated.
Some of the families refused to leave their homes, but those who did were allowed to return to by 7pm.
The building has been disused for seven years.
In June, plans to convert it into flats and a gym were thrown out by Thurrock Council after 500 people signed a petition against it.
Police and the fire service will now mount a joint investigation into the cause of the blaze.