A man is in police custody after a device was thrown into a crowd during an Invasion Day rally in Perth, forcing thousands of marchers to evacuate over bomb fears. WA Police confirmed a device was thrown into the protest crowd on Forrest Place in the CBD, just as speeches were starting about 30 minutes after the rally's 12pm kick off.
"Members of the public that were situated on the upper level on the eastern side of Forrest Place observed a male throw an object down in front of the stage area," Police Commissioner Col Blanch said.
The rally continued, despite the police incident. Picture: Michael Philipps (WA Today)"Police immediately responded. They arrested the person who threw the device and that male indicated that that device may contain explosives."
Police worked with organisers to immediately evacuate 2000 people amid fears of a potential mass-casualty event, Blanch said.
The commissioner said the "very rudimentary device" was about the size of a medium coffee cup.
"The device that was located just in front of the stage area contained ball bearings, contained screws and those items were wrapped around an unknown-at-this-stage liquid in a glass container," he said.
A 31-year-old man from Warwick was in police custody over the matter and was assisting police with their enquiries.
Forrest Place in perth CBD (9News)A house was being searched by police.
"This is a very, very serious incident," Blanch said.
"This is un-Australian and the exact opposite of what we all wanted today to be."
The device did not detonate and no injuries were reported.
They do not believe there is an ongoing threat to the public.
WA premier Roger Cook addressed the media after a device was thrown into the crowd at a Perth Invasion Day rally. (Nine)Forensics are being undertaken to determine whether the device contained explosives, which Blanch said they would find out by tomorrow.
Premier Roger Cook slammed incident as "completely unacceptable".
"This Australia Day should be about unity, not division. That a peaceful protest was targeted in this fashion runs against the very heart of what it means to be Australian," Cook said.
The Invasion Day rally began at 12pm (3pm AEDT) in Forrest Place and protesters gathered for a March for Australia demonstration in Wellington Square at the same time.
The suspended rally was eventually able to resume, where protesters marched through the streets calling for justice for First Nations peoples.