By Aomar Ouali and Karim KebirALGIERS, Algeria -- The Islamist militants who attacked a natural gas plant in the Sahara included two Canadians and a team of explosives experts who had memorized the layout of the sprawling complex and were ready to blow the place sky-high, Algeria's prime minister said Monday. Militants in the highly-organized operation also wore military uniforms and appeared to have help from the inside -- a man from Niger who had once worked as driver at the plant, according to accounts from the prime minister and state television. Algeria detailed a grim toll from the attack, saying that 38 hostages and 29 militants died in four days of mayhem. Three of the attackers were captured and five foreign workers remained unaccounted for, Prime Minister Abdelmalek Sellal told reporters at a news conference in Algiers, the capital. He did not specify the nationalities of the captured militants, report their medical conditions or say where they were being held. Monday's account offered the first Algerian government narrative of the four-day standoff, from the attempted bus hijacking early Wednesday to the moment when the attackers prepared to explode bombs across the gas plant, which spreads out over 5 square kilometers (2 square miles) deep in the desert, 800 miles (1,300 miles) south of Algiers. All but one of the dead hostages -- an Algerian guard -- were foreigners. The dead hostages included seven Japanese workers, six Filipinos, three energy workers each from the U.S. and Britain, two from Romania and one worker from France. The final death toll was still unclear, since accounts from other governments appeared to indicate that more than five workers were still missing. It was also lower than the 81 estimated Sunday from Algerian reports of dead and missing. The militants had said during the standoff that their group included Canadians, and hostages who had escaped recalled hearing at least one of the militants speaking English with a North American accent.