Officers haven't identified the remains found Friday but said they believe the body parts belong to a Caucasian male.
Local police said one officer was hurt in the sting while struggling with one of the suspects over a gun. The officer was hit in the hip area, police said.
Police also recovered 10 passports, according to Maj. Gen. Suwat Chaengyodsuk. He said officers found "certain types of equipment found in the room (that) can be used to produce fake passports."
The official said officers also confiscated three pistols during the raid and found "addictive substances, including ice or methamphetamine."
Thai police identified two of the men taken into custody as James Douglas Eger and Gabel Aaron Thomas. They are American citizens, according to police.
The initial charges against the two are hiding a dead body and possessing a weapon without permission and possessing fake passports. The charges could be changed as the investigation continues, police said.
Police haven't confirmed the nationality and identity of the third suspect.
He has not been formally charged but has been detained at a hospital, police said.