Kurdish-led forces swept into Sinjar, Iraq, on Friday morning, the second day of a major offensive to retake the city, which has been under the brutal domination of the Islamic State for more than 15 months.
Having cut an important supply road east and west of Sinjar, competing units from two Kurdish groups — the pesh merga from the east and the Syrian affiliate of the Kurdistan Workers’ Party, or P.K.K., from the west — fought their way into the center of the city.
Sinjar, which has been battered by American air raids in recent days, including three over a recent 24-hour period, has largely been reduced to ruin. Entire neighborhoods have been leveled, and bombed-out buildings dotted the landscape.
Pesh merga fighters reported that at least one of their members had been killed, as had at least a few dozen Islamic State fighters, but there were no authoritative figures.
Fighting alongside the Kurdish forces were members of the Yazidi religious minority, who were raped, enslaved and killed in large numbers after the Islamic State, also known as ISIS or ISIL, overran the city and Mount Sinjar, to the north, last year.
Before entering the city from the east, Kurdish fighters had to dismantle a tall dirt wall that they had erected to protect themselves from suicide bombers.
A German filmmaker embedded on the front line with the P.K.K. fighters, entering from the west, said they faced almost no fight from the Islamic State.
“There was no resistance — I mean zero,” said the filmmaker, Carsten Stormer.
“We ran down the hill, like in a raid, and the whole time I saw just one dead Daesh fighter,” he said, using the Arabic acronym for the Islamic State. In his section of the fighting, he said, the P.K.K. arrived first, and then the pesh merga.
In the hours before the taking of the city, P.K.K. and pesh merga officials said, they intercepted radio traffic from the Islamic State fighters suggesting that their forces were deserting. They said they had heard the voice of an Islamic State leader berating his fighters, warning that deserters would be beheaded.
The military leader of the P.K.K., who goes by the nom de guerre Agit Kalari, said his forces had taken back the Sinjar mayor’s office, other administrative offices, a major grain silo and the general hospital, as well as several neighborhoods inside the city.
“At 6 a.m. we were in Sinjar,” he said inside a room fortified with sandbags, on the first line of defense inside the city. “We went in four hours before the pesh merga. After we liberated the city, the pesh merga drove up, inside their Toyota Hiluxes.”
On Thursday, the forces took control of a significant stretch of the important supply road, Highway 47, which runs from east to west, and set up trenches to defend the south from an Islamic State counterattack.
Sinjar fell to the Islamic State last year, a development that led to the killing, enslavement and rape of thousands of Yazidis. That prompted the Obama administration to step up its use of air power against the jihadists.