The police were alerted to the center of Filipstad just before 6:00 pm after a badly wounded man was found.
A large police investigation searched the night after suspected perpetrators. The police stopped a car outside of Filipstad and could first seize three people who are reasonably suspected of crimes.
"The move went well, otherwise I can not comment on the initiative," said police word spokesman Mats Öhman.
Later in the evening a fourth man was also suspected of attempted murder. Three of the men are in their twenties, but the police do not want to comment if they are previously known. All four men were arrested later in the night.
The injured man is 30 years old and, according to a report from the central hospital in Karlstad, he has suffered a wound injury, but he is being looked after by the department.