Pro-independence rebels killed a soldier in an attack on his house that left two other people injured, police said Thursday. Sgt. Louis da Costa, 43, was stabbed to death during the attack Wednesday evening by 11 rebels armed with three rifles in the village of Watorete outside Baukau, 160 kilometers (100 miles) east of Dili, capital of the troubled territory of East Timor. Another soldier was injured when gunfire broke out, and a civilian was injured with a stab wound to the head, said Capt. Widodo, the police spokesman in Dili. Some fear escalating violence could postpone or sink a vote, scheduled for Aug. 8, that will allow East Timorese to choose between full independence and autonomy within Indonesia. At least 12 people were killed and another 20 were missing from a rampage by anti-independence militiamen on Sunday, witnesses said. The United Nations is to supervise the vote to be held under an agreement between Portugal, East Timor's former colonial master, and Indonesia, which invaded in 1975. The United Nations plans to send about 300 foreign police officers to the half-island territory to advise Indonesian police, who will have responsibility for law and order. Hundreds of poll monitors and U.N. officials also will be sent in.