Officers said the suspects then fled in three different vehicles, including one that was believed to have used a fake licence plate.
Police said in a statement on Thursday that the man, surnamed Lau, was dumped near the Ching Shan Monastery. He then sought help from pedestrians and was taken to Tuen Mun Hospital with injuries to his head, hands and legs.
Detectives from the West Kowloon regional crime unit are investigating the case, which is currently classified as false imprisonment, wounding and using a false instrument.
A video circulating online showed a half-naked man being ganged up on by a group of men – with one armed with what appeared to be a metal rod – before he was pushed into a seven-seater outside the Mong Kok mall.