Officers were called to the house, in Soi Phatthana 8, Moo 4, Rawai, at about 7pm.
Lt Col Kanaen Somrak of the Chalong Police was initially notified, but due to the nature of the incident Chalong Police Superintendent Col Sarawut Chuprasit and Deputy Superintendent Lt Col Sanan Chanrong were also immediately notified, reported police.
Investigators from the Chalong Police and rescue workers from Rawai Municipality arrived at the scene to find Nakarin Somboon, 18, unconscious and unresponsive, lying in a pool of blood inside the house.
Officers counted at least 10 knife wounds, including a deep stab wound under the right breast.
Rescue workers performed CPR before an EMS Advance unit arrived to rush him to Chalong Hospital, where despite efforts by doctors Mr Nakarin was later pronounced dead.
Officers reported from their initial investigation that a group of teenagers ‒ including three people: “Mr Knot” (real name unknown), “Ms Kwang” (real name unknown), and “Bang” (real last name unknown) ‒ came to the house to attack Mr Nakarin.
During the fight outside the house, Mr Knot stabbed Mr Nakarin while the two were fighting.
The group fled after Mr Nakarin fell to the ground.
Police are now searching for Mr Knot and his associates. Officers are checking footage from CCTV cameras in the area, police said.