The diocese does not yet know what caused it and apologizes to those who could not sleep or thought there was a reason for the ringing.

- We are of course very sad, this should not happen.

We are very aware that it can be alarming if you hear the church bells unexpectedly, says cathedral cook Lena Sjöstrand to Sydsvenskan.

The diocese received information from the alarm center at three o'clock, but they themselves do not know how long the bells had been ringing.

The bells are usually set off manually, but some rings are automatic and managed by a computer system.