Safe house intruders were two men working for an unknown faction who attacked Sayid and Hurley at the safe house. They were both killed by Sayid brutally, but later Hurley was arrested because he had been misinterpreted as the one who responsible for their deaths. It's possible that the intruders, the guy in car and Tony Nagy were working for the same faction.
Over-balcony thrown intruder
The intruder falls over balcony. ("Because You Left")
Sayid and Hurley arrived at the safe house, but Sayid realized the house wasn't safe, so he pushed Hurley away and prepared for a battle. After Sayid took out his gun and opened the door, the first intruder appeared and attacked him. The intruder kicked away Sayid's gun, but Sayid managed to grab him, and threw him over the balcony. As a result, the intruder fell to his death, in front of Hurley.
After the first intruder was killed, the second intruder rushed out from the safe house with his tranquilizer gun, but Sayid pulled him back inside the house, and they started to fight with each other. Eventually, the intruder was impaled on knives which Sayid had conveniently placed beneath his back after he kicked the dishwasher open.
After the deaths of the intruders, Hurley was photographed holding Sayid's gun and misinterpreted as a killer by the pedestrians who found the body of the first intruder. Hurley proceeded to carry Sayid from the scene and transported him to St. Sebastian Hospital, where Jack revived him.