A gas explosion at a clinic in northern Tehran on Tuesday killed at least 19 people, Iran's semi-official news agency ISNA reported.
Hossein Ghanzankari tweeted a clip of a person being lifted into an ambulance, commenting: "Iranian news agency says patients are being evacuated from the medical building in north of Tehran after tonight's explosion".
First responders search for survivors at the scene of an explosion at the Sina Athar health center in the north of Iran's capital Tehran on June 30, 2020.
Firefighters extinguished the blaze several hours later.
The explosion occurred in the underground floors of the building which caused smoke to rise up through the floors, the agency reported, adding that firefighters have been able to localize the fire.
People in nearby Tajrish Bazaar rushed to the site, making a rescue operation hard, authorities said.
The relative of a staff member at Tehran's Sina Athar Clinic weeps after an explosion kills 19 people
The head of the Tehran Emergency Center, Peyman Saberian, initially told the Fars news agency three people had been injured.
Witness Marjan Haghighi told The Associated Press that police blocked roads to the neighborhood.
Earlier in the day, media reports suggested that multiple explosions occurred near Tajrish square in the Iranian capital.
Last week, a blast took place near a military site outside Tehran, with the Defense Ministry saying it was caused by a leak at a gas storage facility.
Parchin is a site suspected of having hosted conventional explosion tests applicable to nuclear power, which the Islamic republic denies.