The four comprise two travellers with European passports, possibly Ukrainian, in addition to two travelling on stolen Austrian and Italian passports, the sources said.
“We have deployed our investigators to look through all the security camera footage. Also, they are interviewing immigration officials who let the imposters through,” said one official with direct knowledge of the investigation.
“Early indications show some sort of a security lapse, but I cannot say any further right now.”
http://www.cbc.ca/news/world/malaysia-airlines-missing-jet-airport-security-breach-probed-1.2565773
Interesting addition . ..thanks!