TEHRAN — An explosion at a medical center in the north of the Iranian capital Tehran killed 19 people on Tuesday, state media reported. Over a dozen others were also injured.

“An explosion and fire broke out at the Sina Athar medical clinic at 8.56 p.m.,” Iran’s emergency services said in a statement carried by the semi-official ISNA news agency.

Fifteen women and four men were killed, and 14 others were injured, the statement said.

Videos posted online showed thick black smoke rising into the evening sky.

Tehran Deputy Governor Hamid Reza Goudarzi told state TV the explosion was caused by a gas leak, but the Tehran Fire Department spokesman Jalal Maleki ruled out a gas leak as the cause of the incident.

“The initial cause of the explosion will be announced after expert investigations, but oxygen and helium capsules were one of the main causes of the blast,” Maleki said.

“The initial cause of the explosion was not a natural gas leak,” he added.

Last week, another explosion took place close to a sensitive military site near Tehran which a defense ministry spokesman told state TV was caused by a tank leak at a gas storage facility.