A man in his 20s was killed and a woman in her 25s was seriously injured in the shooting, which occurred just before midnight on Sunday.
The arrested man is suspected of murder and attempted murder, but police and prosecutors suspect more people are involved.
"We do not suspect that he is the shooter," prosecutor Anders Svensson told TT.
The man was arrested on Monday evening, but the prosecutor would not say where the arrest took place or why the man is a suspect.
The investigation is in full swing and extensive work is still being done, he said.
