Four men have been taken to hospital after they were discovered in a shipping container Thursday morning in the Port of Montreal.

The men, between 30 and 40 years old, were found in the Cast Terminal of the Port of Montreal and taken to Santa Cabrini Hospital.

Urgences Santé spokesperson Francois Labelle said two of the stowaways were in serious condition and having difficulty breathing, but are all now in stable condition.

The men were apparently in the container for three weeks and were suffering from dehydration and heat stroke, he said.

Once the men are in better shape, the illegal migrants, all reportedly from Europe, will be taken to a detention centre in Laval while the Canada Border Services Agency continues to investigate them. They will check if the men have any connection to terrorist groups.

"As this is still under review by the CBSA, and for privacy reasons, we cannot give more information," the CBSA said in a statement.

To date the RCMP has intercepted 3,500 asylum seekers coming into Canada, 2,500 of which are said to have entered through Quebec.

Still, stowaways are considered rather uncommon, said Rivka Augenfield, head of a Quebec coalition of social service agencies that help refugees and new immigrants.

“It’s surprising because I hadn't heard of a case in a long time,” she said, adding that there was a time when stowaways were much more common, but that shipping yards now have increased security to ensure migrants aren’t on board.

“There are what we call ‘carrier sanctions,’ that is the transporter, be it the shipping line, the bus company, the airline, that brings an undocumented person to Canada would have to pay a big fine.”

Augenfield brought up dangerous incidents in the past, such as in 1996, while on a transatlantic voyage to Canada, Romanian stowaways were discovered in a container

The captain ordered them thrown overboard on a makeshift raft, because he didn't want to pay a $5,000 fine.

He was later charged with first-degree murder

“It's never clear whether people understand the potential consequences of what they're doing,” Augenfield said. “It's terrible that people are so desperate that this is what they decide to do.”