Spanish authorities have told more than 160,000 people near Barcelona to stay indoors after a fire at an industrial warehouse released a toxic cloud of chlorine over a wide area.

The blaze, in the coastal city of Vilanova i la Geltrú, south of Barcelona, started at dawn on Saturday in a warehouse storing pool cleaning products, the regional fire service said.

“If you are in the zone that is affected do not leave your home or your place of work,” the Civil Protection Service said on social media.

It advised people to keep doors and windows closed in the at-risk area, which stretched across five local districts along the coast, from Vilanova i la Geltrú to the village of Calafell, near Tarragona.

No casualties had been reported so far, the fire service said on X, adding that it had deployed a large number of units to bring the fire under control.

It said it was “monitoring the column [of gas] caused by the blaze for changes and for its toxic levels”.

The authorities closed roads in the area and shut train stations to prevent people approaching the affected area.

“It is very difficult for chlorine to catch fire but when it does so it is very hard to put it out,” the warehouse owner Jorge Vinuales Alonso told local radio station Rac1.

He said the fire may have been caused by a lithium battery.

The mayor of Vilanova, Juan Luis Ruiz López, told the public TV station TVE that now the fire had been extinguished the authorities expected “this toxic cloud will start to dissipate and we can lift the measures currently imposed”.