'Operation Yellow Bird': How Tiananmen activists fled to freedom through Hong Kong
Inside Hongkongers' unlikely operation to help hundreds of dissidents flee the mainland
It still seems an impossible feat: a group of courageous Hongkongers helping to spirit hundreds of dissidents out of the mainland after the June 4 crackdown under the nose of the authorities.
As the 25th anniversary of the military action looms, evidence obtained by the fills in some of the gaps of the rescue codenamed "Operation Yellow Bird".
Activists would first be rescued and brought to Hong Kong, where they would be placed in safe houses before seeking political asylum overseas.
Watch: Key facilitator of Operation Yellow Bird reveals how Chinese activists entered Hong Kong after June 4 crackdown
Secret codes were adopted to escape Beijing's monitoring in the form of medical bulletins.