At least 24 workers have died in the northern Moroccan city of Tangier after heavy rains flooded an illegal garment factory, the country’s state news agency MAP reported.

Local authorities said firefighters and emergency workers rescued 10 people from the factory, in the basement of a residential villa, as search operations in the flooded factory continued.

The total number of laborers at the site was not immediately known. An investigation was opened.

To meet growing international demand, numerous factories in Morocco, notably in Casablanca and Tangier, rely on unregulated shadow factories to speed up production and meet deadlines.

Factories sub-contract to such illegal units to better compete with cheaper Chinese and Turkish products.

Such hidden factories are mainly located in residential areas and up to 40 people often work in them, sometimes children.

Long hours and low wages are a mark of such illegal work, usually in unsafe conditions, without fire extinguishers, emergency exits and indoor plumbing.