RABAT, Morocco — At least 24 workers died on Monday in the northern Moroccan city of Tangier after heavy rains flooded an illegal garment factory, Morocco’s state news agency MAP reported. There were reports that as many as 28 people died.

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 wasn’t 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 subcontract 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 minors.

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