A 59-year-old man is in serious but stable condition after he was attacked outside the Longueuil metro station Tuesday evening.

Longueuil police say two men got into an altercation on the grass near the east entrance to Longueuil metro on Charles Le Moyne Place about 6:30 p.m., leading to the armed assault.

The victim was rushed to hospital in critical condition, police said.

A 46-year-old man was arrested shortly after the altercation and is meeting with investigators. He is considered an important witness.

“Seconds after it all took place, someone came to officers and told them that this guy was involved in the altercation. Is he really the one who did the assault or was there another suspect?” said Longueuil police spokesperson Tommy Lacroix. "At this time we're just talking maybe about one suspect but we want to be sure and he's now under questioning."

Both men are known to police.

Police put a perimeter in place and are investigating the scene. They are speaking with witnesses and searching for more potential witnesses.

“There a lot of people are coming out from the subway station at that time, but a lot are going into cars right away,” said Lacroix.