A fire and an explosion in a medical clinic in northern Tehran Tuesday evening has killed nineteen people and wounded 14 others.

Emergency services officials announced that the incident occurred at 20:46 in Sina At'har clinic killing 15 women and four men.

Visitors, patients and staff who were on the upper floors of the building suffered most of casualties although the fire and explosion occurred in the basement. IRNA quoted medical sources as saying more than half of all casualties were among doctors and staff in operating rooms.

Spokesman of Tehran’s fire department told local media that firemen immediately got to the scene and rescued 20 more people trapped in the building.

It took firemen two hours to extinguish the blaze and prevent the fire from spreading to adjacent buildings.

The deputy chief of Tehran police Hamid Hedavand said experts, police detectives and fire department investigators are looking into the main cause of the incident.

Later, the police announces that "several people have been arrested" in connection with the incident, including the manager of the building.

The spokesman added that preliminary observation point to a gas leak and a a faulty electrical wire as the source of the incident.