Construction workers at Madora Bay have been threatened by a man who entered a work site with two guns.
Police said the man threatened workers with a loaded shotgun and a pistol.
Nine News reports the man allegedly drove onto the construction site at Madora Beach Road on Wednesday night just as workers were about to go home and pointed the guns at them.
He then stole a work ute, leading police on a chase through Madora Bay that ended at Mandurah police station where he got out and was arrested without incident.
A 23-year-old man has been charged with a number of offences, including armed robbery.
Wormall Civil is offering its employees counselling.
Early voting for Secret Harbour by-election begins Monday
Welfare concerns for missing Swedish national last seen in Warnbro
Wanted man last seen in Golden Bay
Passenger critically injured in West Pinjarra crash
Unregistered painter fined for requesting hefty deposit from Singleton homeowner and not doing the job
Police hunt driver following dangerous Baldivis pursuit
Welfare concerns for boy last seen at Port Kennedy skate park
Rubbish truck catches fire in Baldivis
Driver injured in bus crash in Rockingham