KATHMANDU: An explosion from a gas leak in a medical clinic in northern Tehran has killed 19 people, Iranian state media reported.

Video posted online appeared to show more than one explosion and thick black smoke rising from the Sina At’har clinic.

People in nearby Tajrish Bazaar rushed to the scene, impeding a rescue operation, authorities said. Videos on social media showed people gathered outside of the building.

Hamidreza Goudarzi, deputy Tehran governor, told state TV that a leak from medical gas tanks in the building was the cause of the explosion and fire.

Authorities initially said 13 people were dead, but Tehran fire department spokesman Jalal Maleki later told state TV the toll had risen to 19.

State-run IRNA news agency also quoted Maleki as saying the dead included 15 women and four men. Maleki added that firefighters had rescued 20 people.

State TV said there could be more explosions because there were a number of oxygen tanks remaining in the medical center.

Witness Marjan Haghighi told the Associated Press that police blocked roads to the neighborhood.

(With inputs from Agencies)