The teenage face of Hong Kong's months-long democracy protests struck a defiant note as he turned himself in Friday at police request for possible arrest.

Joshua Wong, 18, flashed a victory sign to supporters while reporting to police headquarters with three other members of his student group.

They're among a number of activists and pro-democracy lawmakers who have been told to go to police to help with the investigation into street protests that authorities declared illegal.

Wong said he and the other group members were prepared to be arrested but would refuse to cooperate.

He vowed that there would be further "Umbrella Movement" protests to come and said any arrests "would just motivate more of the secondary school or university students to come to the street and join the action."

The student-led protesters shut down streets in three areas of the southern Chinese financial hub last fall to demand greater electoral freedom from the Hong Kong government than Beijing is willing to grant. The movement and its youthful leaders gained an initial surge in public support when police unleashed dozens of tear gas rounds against protesters that caught the world's attention. Some protesters used umbrellas to protect themselves, giving the movement a nickname.

But the protests gradually fizzled out as the government ignored activists' calls for the government to drop the Chinese government's requirement that all candidates in 2017 inaugural elections for top leader be screened by a Beijing-friendly panel.

After police cleared out the last protest camp in mid-December, they vowed to investigate and arrest the "principal instigators" within three months.