Hasakeh: US-backed Kurdish forces on Sunday said they had defeated all Islamic State group fighters left inside the Syrian jail that the militants stormed 10 days ago, sparking battles that leftover 370 dead. The Kurdish-led Syrian Democratic Forces (SDF) announced the end of its mopping-up campaign inside the prison “after ending the last pockets in which IS terrorists were present”, according to a statement. IS fighters on January 20 launched their biggest assault in years, attacking the Ghwayran prison in the Kurdish-controlled northeast Syrian city of Hasakeh, aiming to free fellow jihadists. After six days of intense fighting, the SDF announced on Wednesday they had recaptured the prison, but intermittent clashes continued until Saturday between Kurdish fighters and jihadists near the jail. Several IS fighters had been holed up in “northern dormitories” inside the prison, but the SDF on Sunday said they had been defeated. “Thanks to the bravery and determination of the SDF, many of whom paid the ultimate sacrifice, ISIS failed in its efforts to conduct a large-scale prison break to reconstitute its ranks,” US National Security Advisor Jake Sullivan said in a statement. IS gunmen had been hiding in prison “cellars that are difficult to target with airstrikes or infiltrate”, the Syrian Observatory for Human Rights said. The war monitor, which relies on a network of sources inside Syria, said operations were still ongoing near the prison hunting for escaped IS fugitives. “Dozens of IS members managed to escape from Ghwayran prison… in the early hours of the attack,” the war monitor said. It reported that 20 IS fighters had surrendered on Saturday, while the SDF killed another five in an exchange of fire inside the prison. The Britain-based group said 373 people had been killed since the onset of the attack — including 268 jihadists, 98 Kurdish-led fighters, and seven civilians — and warned that the numbers could still rise. The toll jumped from 332 reported earlier Sunday after more bodies of both extremists and Kurdish fighters were found during search operations inside the prison buildings and in areas near the facility, the Observatory said. The SDF had found more than 50 more bodies overnight Saturday to Sunday, the war monitor had reported. On Saturday, an AFP correspondent saw a truck carrying away piles of bodies from an area near the prison, believed to be those of IS fighters. A bulldozer dumped more corpses onto the truck, which then headed to an unknown location. Farhad Shami, who heads the SDF’s media office, told AFP that the bodies would be buried in “remote, dedicated areas” under SDF control. The violence prompted 45,000 people to flee Hasakeh, the United Nations said. Many took refuge in relatives’ homes, while hundreds more slept in the city’s mosques and wedding halls. Syria’s war, which broke out in 2011, has killed close to half a million people and spurred the largest conflict-induced displacement since World War II.