Morocco’s official news agency says 55 people have been killed in a fire at a mattress factory in Casablanca.

About a dozen others were injured, according to a statement by the city government.

The MAP news agency says the blaze broke out on the ground floor of the factory.

Up to 100 firefighters went to work to put out the blaze Saturday morning in Morocco’s biggest city.

The cause of the blaze is not yet known but an investigation has been opened.