Superintendent Chiraphat Pochanaphan of the Patong police told the Phuket Gazette the Australians must face the full extent of the law if convicted. "The suspects opened fire in the middle of a dense tourism area and injured two innocent people. They have seriously tarnished Thailand's reputation."
Shea and Cohen were reported in the Phuket media as being linked to either the Rebels outlaw motorcycle gang or the Bandidos, which local media said was trying to establish itself in Phuket.
Police said the pair had been due to appear in court on Tuesday with a member of the Phuket mafia identified as "Dannie", over a dispute involving a 300,000 baht ($12,000) motorcycle.
After Dannie failed to appear, Shea and Cohen allegedly went hunting for him.
Police say the pair saw Dannie near the Baan Pirin Hotel, and Cohen opened fire with a .38 pistol.
He missed, allegedly hitting the tourists instead, and handed the pistol to Shea before they split up to escape. They were arrested within hours at their tattoo parlour.
Cohen claimed that Dannie had sent men to his home.
"I was afraid he would shoot me since he did not show up at court," Cohen reportedly told police. "So me and my friend decided to make a move first."