A BRADFORD school was evacuated yesterday when a science experiment resulted in a 'violent reaction' and fire.

Around 1,500 pupils were evacuated at around 12.45 after a science teacher at Thornton Grammar School conducted an experiment involving a Bunsen burner and the pyrotechnic compound thermite.

The resultant chemical reaction turned out to be more violent than expected, according to the fire service.

Molten metal fell down the back of a radiator, causing a fire in some rubbish which was extinguished by the science teacher using sand and water.

The chemical reaction also damaged worktops and uPVC windows.

According to the fire service, the experiment, which is common in schools, had been conducted behind a perspex screen and the pupils had been wearing goggles. No-one was hurt.

The fire service was called to the school but the fire was out by the time they arrived.

Michael Smith, watch commander at Fairweather Green fire station, said molten metal had been "spat all over" as a result of the violent reaction.

"The word explosion sounds too extreme. It's more of a violent reaction. Thermite burns like a firework."

"They dealt with it using sand and water. It did cause the school to be evacuated."

The fire service is now carrying out an investigation and it is likely that the Health and Safety Executive will also be looking into what happened.

Mr Smith said the outcome of the experiment had taken "everyone by surprise" and had left people shocked.

He said the batch of thermite may have been a "little bit keen" which had caused the violent reaction.

Mr Smith said he expected the school to review its policy on thermite experiments.

"I have got the fire safety department involved and the fire investigation officer. It's unusual, with it being a violent reaction. It did have the potential to set fire to the school."