Behind the scenes of Hong Kong Airport security

To mark 40 years since it was set up, the Hong Kong Airport Security Unit (ASU) holds an open day on Saturday, September 9, to show local residents how they keep passengers and staff safe. Dogs are used in many aspects of security, searching for possible drugs and explosives. [Photo: Chinanews.com]

Hong Kong Airport Security Unit conducts a drill in front of an audience on the open day celebrating the unit's 40th anniversary, on Saturday, September 9, 2017. [Photo: Chinanews.com]

Airport Security Unit police officers pose for photos in the uniforms from different periods of time since the special unit was formed 40 years ago, during an open day, Saturday, September 9, 2017. [Photo: Chinanews.com]

Weapons used by ASU police officers are on display during an open day to celebrate the 40th anniversary of the founding of the unit, on Saturday, September 9, 2017. [Photo: Chinanews.com]

Children ride on motorcycles used by ASU police officers during an open day held to celebrate the 40th anniversary of their founding in Hong Kong on Saturday, September 9, 2017. [Photo: Chinanews.com]

An ASU police officer poses with a young visitor and a special police vehicle on the open day held to celebrate its 40th anniversary, on Saturday, September 9, 2017. [Photo: Chinanews.com]

Children pose for photos in various uniforms and helmets used by the ASU police officers during an open day held to celebrate the special force's 40th anniversary on Saturday, September 9, 2017. [Photo: Chinanews.com]