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.
Jalal Maleki, the Tehran Fire Department spokesman, told the Tasnim news agency a fire had broken out in a medical clinic in north Tehran, with firefighters sent to the scene.
The head of the Tehran Emergency Center, Peyman Saberian, told the Fars news agency three people had been injured.
Local media is reported the it occurred underground and was probably caused by gas tanks igniting.
The explosion comes days after another blast close to a sensitive military site near Tehran last week.
Speaking on state television, a defence ministry spokesman claimed it was caused by a tank leak at a gas storage facility.
However, there was also speculation that it was an accident at a defence site belonging to the Islamic Revolutionary Guard Corps
This is a breaking news story. Refresh for updates. More to follow
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