Witnesses looked on as a group of men chased a lone man into a residential area in the southern Stockholm suburb of Svedmyra at around lunchtime on Saturday.
One of the men was armed with an axe and the victim was dealt several blows to his person, leaving him nursing serious injuries to the head and back.
The assailant then fled the scene in his car and was later found bleeding profusely at nearby metro station. He was rushed by ambulance to Karolinska University Hospital in Solna.
“What exactly has happened remains unclear. One or more cars fled the crime scene. Then one of the cars crashed into another at a roundabout and a punch up broke out between the drivers,” said Catharina Nordin at Stockholm police to news agency TT.
The cars were later found discarded at the edge of a wood. In one of the cars lay a bloody axe and four people found at the scene were taken in for questioning.
One of the detained had been hit on the head with an iron bar and he was later taken to hospital.
By 8pm in the evening all of those detained had been released from police custody.
According to Stockholm police the attack is probably part of a vendetta. The people involved are known to police but all have declined to cooperate, rendering the facts difficult to establish.