SINJAR, Iraq (AP) -- Iraqi Kurdish militias battling to take back Sinjar from Islamic State militants raised a Kurdish flag and fired off celebratory gunfire in the center of town Friday, though U.S. and Kurdish officials cautioned that it was too soon to declare victory in a major offensive to retake the strategic community.
The Kurdish forces encountered little resistance, at least initially, suggesting that many of the IS fighters may have pulled back in anticipation of Friday's advance. It was also possible that they could be biding their time before striking back.
Kurdish militia fighters known as peshmerga launched a major offensive to retake Sinjar and succeeded in cutting a key nearby highway on Thursday. U.S.-led coalition airstrikes supported the offensive, dubbed Operation Free Sinjar.
Peshmerga Maj. Ghazi Ali, who oversees one of the units involved in the offensive, said thousands of Kurdish fighters entered the town from three directions Friday morning. Associated Press journalists saw them raise a flag over a building in the center of the city.
They encountered minimal resistance during Friday's push, Ali said.
"No one was fighting back. They placed some IEDs and had some snipers in position, but there were no clashes," he said, using the abbreviation for improvised explosive devices, a military term for homemade roadside bombs.
Gunfire fell silent as peshmerga fighters marched into the town. He described the situation in the city as still dangerous, however, and warned that it was too soon to declare victory.
"I can't say the operation is complete because there are still threats remaining inside Sinjar," he said. The risks include ambushes from suicide bombers, roadside bombs and booby-trapped houses, he added.
Iraq's highest Shiite religious authority, Ayatollah Ali al-Sistani, praised peshmerga fighters in his Friday sermon for their efforts to capture Sinjar from the Sunni militant group.
Col. Steven Warren, a spokesman for the U.S.-led coalition, confirmed only that peshmerga fighters raised their flag on grain silos in the eastern part of the town. He said they had not fully retaken Sinjar.
There is reason for officials' caution. An earlier attempt to wrest back control of the town, at the foot of Sinjar Mountain about 50 kilometers (30 miles) from the Syrian border, stalled in December. Militants have since been reinforcing their ranks.
The fight to dislodge IS militants from the Kurdish town of Kobani in northern Syria, meanwhile, took about four months — despite hundreds of U.S. airstrikes in support of the Kurdish fighters.
Islamic State extremists overran Sinjar as they rampaged across Iraq in August 2014, leading to the killing, enslavement and flight of thousands of people from the minority Yazidi community. Its members follow an ancient faith that the Islamic State group considers heretical.
The U.S. later launched an air campaign against the Islamic State militants, also known as ISIL, ISIS and, in Arabic, as Daesh.
Hundreds of pickup trucks and sport-utility vehicles carrying Kurdish fighters were seen gathering at the entrance of Sinjar earlier Friday ahead of a planned push into the town center.
Diar Namo, the 26-year-old deputy commander of the peshmerga unit stationed there, said the skies above Sinjar were largely quiet overnight following intense coalition airstrikes on Thursday.
From his frontline observation post, he said he saw little movement inside the city before Kurdish forces moved in.
"We saw more than 50 Daesh (fighters) flee overnight," Namo said, using an Arabic acronym for the Islamic State group, "Before there were only 200 to 300 in the city."
Officials with the U.S.-led coalition estimated there were between 400 and 550 IS fighters inside Sinjar before the offensive began Thursday.
Southeast of Sinjar, in the village of Soulag, four peshmerga fighters were killed when a homemade bomb targeting their truck exploded, according to fighters in their unit.
Homemade roadside bombs and explosives-laden cars targeting peshmerga convoys significantly slowed Thursday's advance through Sinjar's eastern and western fringe.
The blasts continued Friday. Just an hour after the first Kurdish forces entered Sinjar, an Associated Press team saw an explosion 700 meters (yards) from the northern edge of town.
Ali said he will only consider the operation a success once Sinjar is completely free of land mines and homemade bombs.
"We are waiting on the engineering team," he said, referring to the teams of peshmerga who specialize in diffusing explosives. "Right now, it depends on them."