Rescue services and an ambulance were alerted to Sollentuna swimming hall on Wednesday evening.
– We are on site when you have found a person who was at the bottom. The person was picked up and cardiopulmonary resuscitation was started, says Christer Wahlström, at Attunda Fire Brigade, to Aftonbladet.
The person was not conscious when the ambulance arrived at the scene. It is unclear how badly injured the person is.
The alarm came in to SOS at 18.30.