New Rebels bikie president Jamie Ginn has died suddenly at the Perth Watch House.
Gang Crime Squad detectives took the 50-year-old into custody in Gnangara around 1pm on Tuesday.
He was then taken to the Perth Watch House where he was charged with a number of drug and firearm offences.
Around 7pm, Ginn reportedly had a seizure inside his cell.
"Immediate medical assistance was provided until the arrival of St John WA, however, the man could not be revived," a WA Police spokesperson said.
"The death is not being treated as suspicious and as per standard protocol officers from the Major Crime Division will prepare a report for the Coroner."
Ginn's death comes less than a week after an alleged gangland shooting in Baldivis.
Two Rebels bikies have been charged over the alleged shooting that targeted Mongols bikie Adam Wragg.
Aerial firefighter loses Serpentine home in devastating blaze
Rumours Rockingham councillor Ryan Robertson to be announced as Liberal candidate for Secret Harbour by-election
Baldivis man fined for throwing ex-wife's elderly dog
Concerns for missing woman last seen in Baldivis
Peel Cavaliers break nine-year drought to win Country Championships
City tees up new vision for Kwinana Golf Course
Warnbro man charged with more child abuse, animal cruelty offences
Teen threatened, robbed by offenders on e-scooter in Mandurah
Labor candidate for Secret Harbour Georgia Tree vows to fight for locals