The consulate was attacked on Tuesday as part of protests over at least one U.S.-made movie that mocks the founding of Islam and the Prophet Mohammad. It was the second U.S. facility attacked, following protests earlier in the day in Cairo, Egypt.
Al Jazeera reports that Stevens died of smoke inhalation after the consulate was set on fire. Two U.S. security personnel with him also died.
The two other victims were being evacuated from a safe house when they came under fire, reports Reuters. The consular staff was moved to the safe house following the attacks that killed Stevens.
"It was supposed to be a secret place and we were surprised the armed groups knew about it," Libya's Deputy Interior Minister Wanis Al-Sharif is quoted as saying in the Reuters report.
Later in the day, CNN reported that Stevens was not believed to be the target, and AP reported officials were investigating the possibility the attack was related to the 9/11 anniversary, as well as the video. In any case, officials said the attack appeared to be well-planned.