MONTREAL - A 24-year-old man is in critical condition after he was stabbed in the neck outside Lionel-Groulx metro station Tuesday.

The victim returned inside the station before collapsing, said police.

Police spent several hours at the scene, but were given few details about the circumstances or motive of the attack.

"Quite frankly, it is quite surprising that not a whole lot of people saw anything," said Montreal police Const. Yannick Ouimet, who said it was likely any possible witnesses would have been rushing out of the station due to the rain.

Police do not know how many people were involved in the attack and do not have any suspects.

Trains on both the orange and green lines did not stop at the station for several hours.