Islamic State gunmen fired on civilians fleeing Fallujah, Iraqi officials said Monday, as fighting entered a third week with government forces dug in on the southern outskirts of the militant-held city.

The extremist group’s fighters want people to remain as human shields, said Khalid al-Alwani, a lawmaker from the besieged city. So it is seeking to stop any of the estimated 50,000 civilians in the city from escaping, including by fording the Euphrates River.

...