Airport officials confirm at least four employees have lost their security clearance because of their apparent sympathies towards ISIS.

This comes after a TVA investigation that shows people with employee cards were easily able to board airplanes without anyone being searched.

The TVA investigation aired Tuesday, and said that four employees at the airport have recently had their security clearances scaled back.

According to the program J.E., at least one of those employees posted Islamic State propaganda on their Facebook page, including video of executions.

Another employee had been doing internet searches for weapons and explosives.

One employee was fired, another one left the country, while a third one was reassigned, now working outside of the secure area of the airport.

TVA also found that it was very easy for someone with a restricted access card to wander the airport and secured areas at will.

Authorities with Aeroports de Montreal insist the police and investigators responsible for security at Trudeau airport are doing a good job.

The airport authority issued a statement saying everyone entering restricted areas is searched, but TVA showed video of an individual who was able to walk aboard a plane without ever being stopped, questioned, or searched.

The airport authority also said that employees with security clearance are "regularly investigated and monitored."

"Even if you're vetted, you're still subject to many security measures," said ADM vice-president Pierre-Paul Pharand.

"I say to the public, there are different mechanisms, there are different layers of security to ensure the safety of the travelling public."

There are six Montreal police officers who work at Trudeau airport, with half of them stationed at customs and immigration.

Federal and provincial politicians – including the prime minister – agreed that security is tight, but is closely monitored.

“We will cut not corners when it comes to making sure air travel is safe in this country,” said PM Justin Trudeau. “We've made significant investments and will continue to make investments in keeping Canada's airports and Canadians safe.”

Quebec's Public Security Minister Martin Coiteux said Montreal police, the Sureté du Quebec, and the RCMP are investigating the report of unauthorized intrusions at the airport.

Federal Transportation Minister Marc Garneau said that people with security clearance at airports are subjected to daily verification checks by police.

"When criminal activity is identified, we take immediate action and can suspend or revoke the clearance of an individual. As part of our ongoing security protocols, more than 1,100 clearances have been refused or cancelled at airports across the country over the past two years,' wrote Garneau.

Trudeau airport also had to answer to criticism that there are never more than six armed police officers patrolling the airport at all times, a far cry from U.S. airports, where police are ready to intervene at a moment's notice if there's an attack or a tragedy.

“Those police officers will be the first wave with their colleagues from Station 7 in Saint-Laurent or Station 5 in Dorval-Pointe-Claire, which are not very far,” said Montreal police assistant director Patrick Lalonde.

Security expert Claude Sarrazin of Sirco Security said Montreal has been lucky so far.

“We have fair security because of our location, luckily enough that has prevented attacks so far,” he said. “That doesn't mean it will not happen. We can keep calm for the moment, being but we need to look into these things.”