The incident is said to have taken place clost to the Tajrish Square, north of Tehran, with suggestions the building was a health centre. Those at the scene say the cause of the explosion is unknown.
Newsweek reporter Tom O’Connor tweeted: “Following reports of an explosion at northern Tehran, Iran’s Tajrish Metro Station.”
Footage on social media showed plumes of black smoke rising high in the sky over the city, together with flames.
Midway through the clip there is a second, very loud blast.
Zillay Shah tweeted: “The cause of explosion is still not known.”
Journalist Kian Sharifi posted: “A spokesman for the fire department confirms to Fars news that a health care centre is on fire in northern Tehran, saying ‘people may be trapped inside’.”
Semi-official Iranian news agency ISNA has also reported on the explosions, without citing any additional information.
The explosion comes days after another blast close to an Iranian missile facility earlier this week.
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