The man who shot and killed another NASA worker before turning the gun on himself was undergoing a job review for poor performance and feared being fired, officials said tonight.

Nasa is concentrating on a review of its security procedures as officials try to figure out today how a contract worker smuggled a handgun into the Johnson Space Centre, where he killed another employee and himself.

A 60-year-old Nasa contract worker took a handgun inside an office building at the Johnson Space Centre and shot dead a hostage before killing himself.