People living near a “toxic cloud” from a burning tyre dump near the Spanish capital Madrid have been told to leave their homes.
Local officials ordered the evacuation of the Quinon de Sesena area, where 9,000 people live, saying human health might be at risk.
However, many residents have already left their homes and it is thought that just 1,000 people are still there.
Investigators believe the fire was started deliberately early on Friday.
Emergency services were called to the town of Sesena, 35 km (22 miles) south of Madrid, at 01:00 local time (23:00 GMT on Thursday).
They sent 10 teams of fire-fighters, who have battled the blaze all day.
Some schools stayed closed for the day. There are no reports of any injuries.
The Castilla La Mancha government said it is unlikely wind will disperse the smoke from the millions of burning tyres.
A spokesperson said the decision to evacuate had been taken “to avoid risk”.
People will be taken to a sports centre and several schools in buses. Ambulances will be made available for sick people to travel in.
A pulmonologist, Carmen Diego, told the TV channel Antena 3 (in Spanish) that inhaling large amounts of the smoke could cause chemical pneumonia and eye, nose and throat irritation, especially in children, old people and those with weak respiratory systems.
The Madrid government said on Friday evening that the city’s air quality had not registered any change from the fire in the nearby town.
The president of the regional government, Emiliano Garcia-Page, visited the town on Friday.
He said: “I’ve been talking to the two petrol station workers who raised the alarm, and they told me that the fire started on one side of the dump, which makes us think it was not a chance occurrence. Besides, it was not that hot last night.
“But for now we are not drawing any conclusions.”
Drivers on roads nearby have been told to keep their car windows up as the smoke may damage their health.
Flight departures and arrivals at Madrid airport have not been affected.
The sprawling dump has attracted criticism from locals and environmentalists for years.