Seven people were injured in the bloody attack on Wednesday.
According to the police, the situation is life-threatening for three of them, and they are being cared for in hospital.
The attack is classified as attempted murder, but the police are working to investigate possible terrorist motives.
Moved to Vetlanda last year
The man who the police were able to quickly arrest yesterday afternoon is an Afghan citizen in his 20s who came to Sweden in 2018. According to the population register, he moved to Vetlanda in April last year.
Must have acted alone
In connection with the arrest, he was shot and taken to hospital.
He should still be alive.
The man is said to have acted alone, and he has been known by the police since before for minor crimes.
Säpo is now cooperating with the police in the case.
During the night, the police conducted a house search in the man's home.
Later on Thursday, the police will hold a press conference about the situation in the investigation.