The alarm came to the rescue service shortly after 11 o'clock on Wednesday morning.
The police state that there has been a loud bang.
Several windows in a property on Första långgatan are broken and there are broken glass on the street.
- The explosion took place on the third floor of the property.
What is in the property is a doctor's office, said Anna Göransson, press spokesperson at the police region West.
Two injured
According to SOS Alarm, two people are injured and have been taken to hospital.
Later in the afternoon, Sahlgrenska's press office announces that the injured are two women, one in the 85-year-old who is seriously injured and one in the 40-year-old who is slightly injured.
- It is about two patients, says Peter Adlersson, the police's press spokesperson.
Peter Adlersson also says that there is information that the explosion took place inside a toilet.
Were there a lot of people at the scene when the explosion took place?
- There is no information on how many people were in the room or outside.
But it is an area where a lot of people move, says Anna Göransson.
- There is no damage to adjacent businesses.
Photo: Erika Arnadottir / SVT
Unclear what exploded
In connection with the explosion, a large area between Järntorget and Masthuggstorget was cordoned off.
About an hour and a half later, the roadblocks had been lifted and car and tram traffic could start rolling again as usual.
Police and rescue workers are still at the scene and the National Bomb Squad has been called in to find out what caused the explosion.
A preliminary investigation into, among other things, attempted murder and general destruction has been initiated.
- We are looking for a man who should have been visible inside the clinic and who could possibly be the perpetrator.
At the moment, we have no arrests, says Thomas Fuxborg.
Less than a month ago, there was another explosion on the same street.
The police do not want to say if there is any connection.
- We do not know yet, but we will of course look at whether there is a connection, says Anna Göransson.
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Hear SVT's reporter Oscar Barragan describe the situation at the site after the explosion on Första långgatan in Gothenburg.
Photo: SVT