Around 420 people were evacuated from a food production factory after a pizza on a conveyor belt caught fire.
Although the fire service was called, a sprinkler system was said to have extinguished the fire. Firefighters inspected a pizza oven with a thermal imaging camera to check it was safe before leaving the scene.
Two fire engines and ten firefighters attended the incident in Harrow.
It is not known what toppings the pizza had.