Canadian Terrorists on Flight from London?

From CKNW (a talk radio station in Vancouver):

RICHMOND/CKNW(AM980) - Air Canada says it may have been young people acting up on a flight from London, England to Vancouver, but passengers onboard the flight say otherwise.There were some tense moments as the Air Canada plane sat on the tarmac of London's Heathrow Airport.

Vancouver passenger, Ivan Bulic says British police boarded the plane and told them to stay in their seats, while five males were dragged off the plane, "When police came onboard, heavily-armed police with bullet-proof vests and dogs, and two busloads of police surrounded the aircraft, people were obvioulsy wondering what was going on."

There was a second story on this in the Vancouver Sun behind their entry screen, but otherwise I have heard nothing about it. Just nerves on the part of the police or something real?