At 3pm, Karon police arrested Ben (real name not disclosed) 16, Johnson (real name not disclosed) 17, Pon (real name not disclosed) 17, and seized a sheath knife.
After their arrests, the three confessed to the crime and claimed that the woman, Sukanlaya Saetio, 25, was the leader of the gang and the robbery was her idea.
Police charged all three boys with attempted robbery, using a get-away vehicle and assault with a knife.
The incident took place at around 12:30am when Herbert Wunderer, 59, and Karin Katherina, 54, were walking along the beach on their way back to their room at the Hilton Phuket Acadia Resort in Karon.
Two motorbikes suddenly approached them, and one of the riders attempted to snatch Ms Karin’s purse from her.
Mr Herbert pulled the purse back but the suspect reacted by stabbing him in the arm. The gang then then sped away towards Karon circle, without the bag.
After the incident was reported, Mr Herbert received first aid while police checked CCTV footage. They spotted four suspects on two motorbikes heading towards Chalong.
Police learned that Johnson was the one who stabbed Mr Herbert and arrested him in front of Municipal School in Phuket Town.
Police later arrested Ben and Pon at their rented room in Rassada. They are still searching for Sukanlaya who, at time of going to press, remained at large.