A powerful explosion at a clinic in northern Tehran killed at least 19 people on Tuesday, Trend reports citing AFP.
The blast at Sina At'har health centre caused damage to buildings in the vicinity and sent a plume of thick black smoke into the night sky, state television reported.
"An explosion was reported at 20:56 (1626 GMT) followed by a fire at Sina At'har clinic. Medical units were dispatched immediately," Tehran's emergency medical services said in a statement.
"The death of 13 people has been confirmed. Six have also been injured and transferred" to a hospital, it added.
Tehran fire department spokesman Jalal Maleki also told the agency that firefighters recovered six more who died after the blaze was extinguished around two hours later, raising the toll to 19.
Fifteen of the dead were women, state television said.
In a TV interview, Maleki said the explosion occurred as gas canisters caught fire in the clinic's basement.
Some of the victims "were in upper floors in operation rooms, who were either patients being operated on or those with them," he said.
"They unfortunately lost their lives due to the heat and thick smoke."
The incident comes four days after an explosion near a military complex rocked the Iranian capital.
It took place in the Parchin area in the southeast of Tehran due to "leaking gas tanks", Iran's defence ministry said on Friday, adding there were no casualties.
23:29 (GMT+4) An explosion has taken place in north Tehran, Iran’s ISNA news agency reported on Tuesday, without citing the reason for the blast or any additional information, Trend reports citing Reuters.
Video posted online by the agency showed thick black smoke rising into the evening sky.
Jalal Maleki, the Tehran Fire Department spokesman, told the Tasnim news agency that a fire had broken out in a medical clinic in north Tehran and firefighters have been sent to the scene.
The head of the Tehran Emergency Center, Peyman Saberian, told the Fars news agency that three people have been injured in the fire.
An explosion took place close to a sensitive military site near Tehran last week which a defence ministry spokesman told state TV was caused by a tank leak at a gas storage facility.