Firefighters in Leamington Spa, central England, were on Friday tackling a huge blaze which engulfed an industrial plant in the town, prompting road closures and the evacuation of surrounding properties.
Explosions and the stench of chemicals have been reported, although Warwickshire Police said it was too early to determine whether there were any casualties.
As an additional precaution, people living within 70 metres of the site were urged to shut doors and windows by West Midlands Ambulance Service.
Local resident Mike Brown tweeted a video of the huge plumes of thick, black smoke.
Labour Member of Parliament for the spa town, Matt Western, said the fire may involve chemicals from a plastics business unit.
West Midlands Ambulance Service said it had two paramedic officers and a Hazardous Area Response Team at the scene.