Police have detained seven local men aged between 20 and 30, who were suspected of assaulting an exhibitionist to death at Section 17, Shah Alam on Sunday.

Selangor police chief Datuk Abdul Samah Mat said in the incident around 2am, the group was believed to have reacted to the screams for help of a woman in her 20s, whom the man had exposed his genitals to.

"Police are still investigating, and at this point there is no other motive other than that the public were infuriated with him," he told reporters after the handing over of duties of the Serdang district police chief at the police district headquarters here on Monday.

According to Abdul Samah, the suspects had tied up the man's hands before beating him up.

"He was already unconscious when police arrived. No weapon was found at the scene," he said, adding that more suspects could have been involved in the assault.

He said the body of the man was sent to Klang Hospital for post-mortem.