Several people have been arrested after the fight broke out in Umeå on Thursday night, reported the TT news agency.
The crime has been labeled as aggravated assault, but it may be altered to attempted manslaughter.
"This is not an ordinary fight between youths, we're sure about that much," said Uno Nilsson of the local police.
"The chance of this being gang-related is quite high."
It remains unknown if those apprehended were already known to police.