FIGHTING IN AFGHAN OFFENSIVE NARROWS, COMMANDERS SAY (WITH AFGHAN-FIGHTING) C.J. Chivers contributed reporting from Marjah, Afghanistan; Rod Nordland from Kabul; and an employee of The New York Times from Helmand province. NAD ALI, Afghanistan -- As heavy fighting in the insurgent stronghold of Marjah carried into its third day, the number of Taliban fighters in the area has dropped by about half, U.S. and Afghan commanders said Monday. About a quarter of the 400 Taliban fighters estimated to be in Marjah when the Afghan-U.S. operation began early Saturday have been killed, officers said. A similar number of Taliban appear to have fled the area, including most of the leaders, and local Afghans were offering help ferreting out Taliban fighters and hidden bombs, they said. But intense fighting on the ground through much of the day indicated that there were plenty of Taliban insurgents with fight left in them. In Marjah itself, a broad agricultural area crisscrossed by irrigation canals, the fighting appeared to be concentrated in two areas, at the northern end of the district and at the center. There, the combat on Monday continued at a furious pace. Among the Taliban fighters still in Marjah, U.S. and Afghan officials said, morale appears to be eroding fast, in part because the holdouts feel abandoned by their leaders and by local Afghans who are refusing to shelter them. 'They cannot feed themselves, they cannot sustain themselves -- that is what we are hearing,' Col. Scott Hartsell told a group of senior officers at a briefing near Marjah that included Gen. Stanley A. McChrystal, the commander of NATO forces; and Abdul Rahim Wardak, the Afghan minister of defense. 'They are calling for help and they are not getting any.' 'Pretty soon, they are going to run out of gas,'' Hartsell said. Some of the U.S. and Afghan commanders said that they hoped to complete the combat phase of the operation within three or four days. The details of the assessment, the most extensive made public on the Marjah operation, could not be independently verified. But whatever the accuracy of the briefing, it did not lessen the ferocity of the battle at various points on the ground. With the sort of hit-and-run tactics they were employing, small numbers of guerrillas appeared capable of holding out for long periods, and exacting the maximum effort from the NATO and Afghan forces to defeat them. One of the most striking developments on Monday came from a group of tribal elders, who confirmed that they had begun to actively assist the U.S. and Afghan government in the fighting. A Marjah tribal elder, speaking on the condition of anonymity, said that a local shura -- or council -- had assigned 10 local Afghans to assist U.S. and Afghan military units. 'They are here to help us, and it's our duty to help them,' a tribal elder said in a telephone interview, speaking on the condition of anonymity. 'They might kill me for telling you this.' Despite the encouraging reports from the field, the U.S. military and Afghan government had to contend with plenty of difficulties, in Marjah and in other locations. There were conflicting accounts of a missile strike that killed at least 11 civilians on Sunday. U.S. officials said they had in fact hit the target they intended, a description that did not match accounts from Marines and other witnesses on the ground. NATO officials said on Monday that eight Afghan civilians were killed and three wounded in four separate episodes, three of which occurred inside the area where the Marjah operation was unfolding. Three civilians were killed in Marjah: one in crossfire during a gun battle and two others who were shot when they did not heed warnings from NATO and Afghan forces to keep their distance. Also Monday, five civilians were killed and two were wounded in an airstrike in Zhari, a district in neighboring Kandahar province. A patrol of Afghan and NATO forces spotted a group of residents digging a ditch on the roadside, and they mistook them for insurgents planting a bomb. They called in an airstrike. The heavy civilian toll highlighted the stressful and confusing nature of the fighting, especially in Marjah, and of the difficulties inherent in conducting military operations in a guerrilla war, where insurgents can hide easily among the population. Still, the deaths are troubling to the U.S. and NATO commanders, who have made protecting civilians the overriding objective of their campaign -- even when doing so comes at the expense of letting insurgents get away. The stream of news releases flowing from NATO headquarters detailing the episodes is testament to have how seriously military commanders here take the problem. The missile strike in Marjah on Sunday remained shrouded in mystery, despite attempts to clarify what had happened. A U.S. rocket fired into a mud-walled compound during a firefight killed at least 11 people. After the strike, the U.S. military said the rocket had struck the wrong house and apologized for the civilian loss of life. On Monday, however, U.S. officers said that the rocket, fired from miles away, had in fact hit the compound it was intended to hit. Marines were taking fire from that compound, officers said, so the compound was attacked. They did not realize that there were civilians inside. 'The rocket hit the house that we wanted it to hit,' a U.S. officer said at a briefing the briefing with McChrystal and Wardak. 'We didn't know there were civilians there.' But that explanation did not square with accounts from Marines on the ground, where a New York Times reporter embedded with a company witnessed the episode. The Marine company commander said that he and his men were startled by the missile strike, of which they had no prior warning. Earlier in the day, the company commander said, he had requested a rocket to be launched at a building next to the one that was eventually hit, from which the Marines were taking small-arms fire. The permission was denied, he said. As the day wore on, one of the biggest unknowns was the whereabouts of the fleeing Taliban fighters. Intelligence reports indicated that a group of Taliban had fled north, to the town of Sangin, while a number had fled south toward the border with Pakistan. Some U.S. officers said they suspected some fighters -- especially the local ones -- probably just decided not to fight. That is part of the nature of a war like this: if guerrillas decide to stay home, they are unlikely to be discovered. Which means, of course, that they can fight again. As for the other fleeing insurgents, there were plenty of places for them to go. Of Helmand province's 13 districts, at least three are not under the government's control. And some reports had insurgents fleeing to Pakistan, where the Taliban's senior leadership resides. 'The Taliban have no specific uniform; they are like ordinary people,' said Abdul Razaq, a tribal elder from Marjah. 'They can go anywhere, anytime.' 