CBS News has learned one of the four American soldiers killed in the ambush in Niger may have been kidnapped by Islamic militants who opened fire on a group of U.S. and Nigerien troops in early October. 
 
 The Pentagon has not said how Sgt. La David Johnson became separated from the other soldiers. 
 
 Hundreds of bullet casings and bushes stained with blood are evidence of just how intense the fighting was at the site where the group of American and Nigerien soldiers came under heavy fire. 
 
 Terrified villagers said the battled raged on for more than two hours. 
 
 The troops had stopped for supplies in the village of Tongo Tongo when heavily armed attackers appeared on motorbikes and started shooting. 
 
 CBS News 
 
 Initially, a few fighters from a group linked to the Islamic State of Iraq and Syria (ISIS) drew the troops to this spot. They burnt down that school and then pushed them in this direction to where the ambush actually took place. 
 
 When it was over, village elder Adamou Bububaker said he saw three U.S. soldiers slumped dead in their truck. 
 
 "Two of the bodies were in the vehicle and another on the ground," he said. They had been stripped of their uniforms. 
 
 But Johnson's body was found two days later, about a half a mile away. Nigerien military sources tell CBS News they believe ISIS fighters decided to try and kidnap Johnson. 
 
 The fighters later shot him and dumped his body in the bushes, his hands roped together. 
 
 Inside the Niger village where U.S. soldiers were ambushed 
 
 Nigerien military sources insist the mission was to capture a terrorist leader and not focused on reconnaissance, as the Pentagon has stated. Either way, the soldiers had been instructed to stay overnight in territory where more than a dozen extremist groups are operating. 
 
 Asked if they were taking too big of a risk, one Nigerien soldier would only answer if we did not show his face. 
 
 "Do you think you were taking too big a risk?" Patta asks. 
 
 "The Americans? Yes, they took a risk," the soldier says. ||||| PENTAGON -- Details of the ambush in Niger are slowly emerging more than three weeks after four U.S. soldiers were killed. The Americans were part of a larger group looking for an Islamic militant, but his fighters found them first. 
 
 The patrol that was ambushed was tracking a terrorist, Adnan Abu Walid al Sahraoui, the leader of an Islamic State of Iraq and Syria (ISIS) offshoot that operates in western Niger. 
 
 On Thursday, the Pentagon acknowledged for the first time that there was a second team of U.S. and Nigerien forces was on the ground. 
 
 Lt. Gen. Frank McKenzie briefs reports on the ambush in Niger that killed 4 Americans. CBS News 
 
 "There was one that had something to do with this operation but I'm not going to be able to give you any more specific details about what happened until we complete the process of the investigation," said Lt. Gen. Frank McKenzie. 
 
 CBS News has learned that the second team was on a kill or capture mission for al Sahraoui. But it was called off after he slipped across the border into Mali. 
 
 ISIS offshoot likely connected to Niger ambush 
 
 Instead, the patrol with 12 Americans and 30 Nigeriens was told to investigate an area where the terrorist had been. The patrol was also told not to expect enemy contact. 
 
 After gathering intelligence, the men stopped in the village of Tongo Tongo. They were ambused by al Sahraoui's fighters as they left. Sources say the U.S. team did immediately alert their commanders they were taking fire. But the patrol waited an hour before asking for help. 
 
 French special operations forces were among the first to respond to the U.S. call for help during an ambush in Niger. CBS News 
 
 "You know, we look at that hour pretty hard ourselves, but again there are a lot of reasons why that time could've elapsed like that," McKenzie said. 
 
 Investigators still do not know how Sgt. La David Johnson got separated from the other soldiers during the attack. His body was recovered two days later. 
 
 CBS News learned on Thursday that a French special operations team was the first ground force to respond to the call for help from troops from the U.S.-Nigerien patrol when they were attacked on Oct. 4. The French team was on the scene within 3-4 hours of the call, after the French military sent jets from Niger's capital, Niamey, and Mali, a source said. 
 
 The U.S. military is still unsure how Army Sgt. La David Johnson became separated from forces on the ground in Niger. CBS News 
 
 Military officials briefed members of Congress Thursday. Democrat Richard Blumental said he had questions about the mission of the roughly 6,000 U.S. troops stationed in Africa. 
 
 "One of the reasons for this tragic catastrophe in Niger may well have been lacking resources in intelligence that could have permitted them to avoid that ambush," Blumenthal told CBS News.
– One of four American soldiers killed in Niger last month may have been kidnapped by ISIS-linked militants before he was executed, sources say. A village elder in northern Niger tells CBS that a battle raged for more than two hours after a group of Green Berets was ambushed by attackers on motorbikes. He says after the battle was over, he saw three American soldiers dead in a truck, stripped of their uniforms. The body of Sgt. La David Johnson, however, was not found for two days and military sources tell CBS that they believe he was taken prisoner by militant who later shot him and dumped the body around half a mile away from the battle site. The military is investigating how the four soldiers became separated from their unit during the Oct.4 attack while seven other American troops were reportedly evacuated. Five Nigerien troops were also killed in the attack, though sources tell the Guardian that the Nigerian forces fled soon after the ambush, leaving the Americans to fight alone. The sources say the trapped American troops struggled to call in an attack from nearby French forces, who complained about bad weather and rough terrain. (The attack has been called a "massive intelligence failure.")