Hundreds of thousands of civilians are trapped in Mosul, aid agencies warned Monday, with U.S.-led forces refusing to create safe escape routes and urging residents instead to “shelter in place” as the military assault on ISIS (Islamic State) fighters swiftly moves into the Iraqi city.

“Our main concern now is that operations are getting more and more close to Mosul, so we think it’s now a huge need to ensure the people inside Mosul have a safe way to get out of the city,” Fanny Mraz, the head of mission in Iraq for Handicap International, an organization that helps victims of land mines and other improvised explosive devices, told U.S. News and World Report.

“Without a clear path to allow innocents to flee, Mosul’s estimated 1 million-1.5 million remaining civilians will be stuck as the coalition of Iraqi units begins to root out as many as 5,000 Islamic State group fighters holed up in the encircled city, and as many as 2,000 others in the surrounding area,” U.S. News and World Report writes.

“The United Nations has long estimated that the battle could displace at least 1 million people, worsening the country’s humanitarian crisis, and the agency’s high commissioner for refugees Filippo Grandi said from Baghdad […] that protection of civilians should be ‘the most important element of this operation,'” as Common Dreams reported when the Mosul offensive began last month.

Yet, when approached Monday by U.S. News and World Report about the coalition’s failure to create a so-called humanitarian corridor for civilians, Pentagon spokesman Peter Cook “was less concerned about the likelihood of a mass migration and deferred to Baghdad’s current plan to encourage Mosul civilians to stay in their homes,” the outlet reports. “Iraqi air force planes have dropped leaflets on Mosul in recent weeks saying the safest thing for residents is to shelter in place.”

Fears for civilians’ lives are growing increasingly urgent as new reports emerge that U.S.-led coalition bombs killed a family of eight near the city on October 22.