A gas leak Tuesday at a medical clinic in Tehran caused an explosion that killed at least 19 people, according to Iranian state media.

Authorities initially said 13 people were dead. Jalal Maleki, a spokesman for the Tehran Fire Department, later told state TV that the toll had risen to 19.

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

First responders gather at the scene of an explosion at the Sina At'har health centre in the north of Iran's capital Tehran northern Tehran on June 30, 2020. (AFP via Getty Images)

Fars News agency reported that at least six people had been injured.

Video posted online appeared to show more than one explosion and thick black smoke rising from the flames. Other video showed firefighters using a ladder to access the roof.

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

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.

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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.

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Deputy Health Minister Iraj Harirchi told state TV the clinic had 25 employees at the time of the blast and primarily carries out light surgeries, Reuters reported.

The Associated Press contributed to this report.

Tehran medical clinic explosion kills at least 13, state media report

A Deputy Health Minister told state TV there 25 employees in the building at the time of the explosion.