Casablanca, Morocco: A fire on Saturday in a mattress factory in Casablanca, Morocco's economic hub, killed 55 people and injured a dozen others, the official news agency quoted local authorities as saying.

A statement by the Wilaya of Greater Casablanca, the city government, said 55 people were killed in the morning fire and 12 injured. The MAP news agency had earlier reported 25 deaths.

About 100 firefighters rushed to the scene in an industrial sector of Casablanca. The blaze began on the ground floor of the factory at about 10 a.m. (1000 GMT) and quickly spread through the five-story building, MAP reported.

The official statement cited the presence of chemical products in the factory as responsible for the fire's rapid spread. However, the exact cause was not immediately known.

Firefighters battled the flames for three hours.

Officials from the prosecutors office visited the scene, then opened an investigation to determine the cause of the blaze and any responsibility, the news agency said. That was in line with standard procedure.

Local officials also rushed to the scene to help supervise rescue operations, MAP reported.

The bustling coastal city of Casablanca is Morocco's leading port and the economic capital of this North African country. It reflects the contrasts of Morocco, the westernmost Muslim country, with its rich modernity and poor, crowded neighborhoods with soaring unemployment.