The hijacking of a CanJet airplane at a Jamaican airport late Sunday night indicates how vulnerable airports are to a "desperate or determined" individual who is intent on breaching security, says a former CSIS intelligence officer.

A gunman in his 20s described as having mental health issues stormed a CanJet plane at Sangster International Airport in Montego Bay, at first holding 174 passengers and eight crew hostage.

After releasing the passengers and two crew members, he held the remaining six crew members until they were freed early Monday morning.

Michel Juneau-Katsuya, a former intelligence officer with the Canadian Security Intelligence Service (CSIS), said the incident demonstrates that an airport is one of the most difficult environments to secure.

Hundreds, if not thousands, of people and vehicles arrive and depart every hour, and it's a huge geographical space with various access points that are difficult to control, Juneau-Katsuya told CTV Newsnet.

"(The incident) reveals again how vulnerable the air industry is to desperate or determined individuals who could go in and do all sorts of things."

While no one was injured in the incident and the gunman is in police custody, the fact that a man carrying a firearm was able to get past security checkpoints and then onto the tarmac and the aircraft, raises important questions about security at Sangster International.

Prime Minister Stephen Harper was travelling to Jamaica from this weekend's Summit of the Americas in Trinidad and Tobago, and security should have been "at its highest level, and we've got a depressed individual who was capable of sneaking through," Juneau-Katsuya said.

The fact that such an international airport could have such lax security is inexcusable, and Sangster's entire security system needs urgent renewal, added Peter St. John, a terrorism and intelligence specialist who is a senior scholar at the University of Manitoba.

"Now, every terrorist and every would-be hijacker in the world knows there are no guns at the Montego airport and a lot of Canadians go through that airport," St. John told CTV Newsnet from Winnipeg. "And Canadians, if they know there's not proper security, they're not going to go through that airport."

According to security expert Alan Bell, the CanJet crew should be commended for convincing the gunman to release the passengers, which made dealing with the situation much easier for law enforcement officials on the ground.

"The more people you take off the plane, it's easier to identify the targets and therefore it's easier to take down as opposed to trying to fight your way through an aircraft with 200 or 300 people panicking and running around like headless chickens," Bell told Canada AM.

While it is still unclear exactly what happened on the aircraft, it is likely that highly trained military personnel, much like the Canadian Forces' JTF2, were on the ground surrounding the plane and trying to make contact with the gunman, Juneau-Katsuya said.

They were also likely attempting to get cameras close to the plane to set up listening devices and cameras to find out what was going on inside, he said.

What is clear is that their job was made easier by the fact that the gunman was open to negotiation, as demonstrated by the fact that he was willing to release the passengers.

Jamaican authorities will have to launch an investigation into how the security breach occurred to reassure dignitaries, tourists and pilots that flying to Montego Bay is still safe.

According to Bell, pilots have a list of airports that they won't fly to because of security concerns.

"Some are in the Caribbean, which relies heavily on the tourism industry," Bell said. "If they can't guarantee safety and security, pilots will simply refuse to fly into those airports."