MOSUL, Iraq — They came by the hundreds — men, women and children fleeing the battle for Mosul, some bloodied and crying out for help. So large was the crowd on the road that Iraqi troops initially ordered them back, worried that an Islamic State suicide bomber could be hiding among them.

Mosul’s residents are fleeing in growing numbers as Iraqi forces push deeper into the country’s second largest city, and the battle-hardened extremists are fighting for every block, exploiting the dense urban terrain and using civilians as human shields.

On Wednesday the tide of displaced people reached the Samah district, where Iraqi medics treated dozens of wounded, including at least six soldiers.

At one point, four children and a man from the same family were rushed into the station, bleeding heavily as their relatives wailed in grief. A mortar round had slammed into the inner courtyard of their home. A few minutes after being brought to the aid station, a 16-month-old girl with a head wound was pronounced dead.

Then the main rush came — hundreds of civilians racing forward on a dirt road. The troops ordered them to halt, saying they had intelligence that IS might send suicide bombers disguised as civilians. One of the men raised his shirt to show that he wasn’t armed, saying he was desperate for food.

Mosul, which fell to IS in the summer of 2014, is still home to more than 1 million people. Fearing a mass exodus, authorities have urged residents to stay inside their homes. But the presence of civilians has prevented the U.S.-backed Iraqi forces from using overwhelming force, slowing their advance and prolonging the city’s agony.