Fallujah-Iraqi forces radioed the U.S.-led coalition for air cover as they evacuated their casualties: One member of a police bomb-disposal team had been killed and two others had been wounded as they dismantled part of the complex network of booby traps on the edge of ISIS-held Fallujah.

Another team pushed on, attempting to clear a recently secured neighborhood on the southern side of the city, the occasional explosion kicking orange dust into the air as part of the painstaking work.

Nevertheless, a few hours later, that team was hit by an explosion as its members defused a bomb, and two soldiers were seriously injured.

“It’s one of the worst jobs in the entire world,” Col. Arkan Fadhil of Iraq’s special forces said after radioing for another team, this time a group of tribal fighters trained by the United States in bomb-disposal techniques.

On Friday morning alone, Iraqi engineering teams had encountered 25 improvised bombs in a stretch of just 500 feet, he said.

Notably, ISIS has had more than two years to barricade itself into Fallujah, the city west of Baghdad that was the first in the country to fall to the militant group.

After launching an offensive for the city last month, Iraqi Special Forces are now within two miles of the city’s center, but extensive tunnel networks used by the militants and deadly roadside bombs are slowing their progress.

In a group of semi-constructed buildings on the city’s outskirts, Iraq’s elite counterterrorism forces have set up a makeshift base.

Bullet and mortar holes pockmark the skeletons of unfinished concrete structures, where soldiers and police officers use unfinished rooms to lie down and rest, blankets laid out on the floor next to piles of sandbags.

It’s a high-stakes fight for Iraqi Prime Minister Haider al-Abadi, with the battle distracting from a political crisis that has brought regular demonstrations and seen protesters ransack parliament and his office, demanding reform.

Iraqi commanders have also argued that clearing the city is a priority because of its proximity to Baghdad, just 45 miles to the east.

For his part, Lt. Gen. Abdulwahab al-Saedi, head of the Fallujah operation, pointed out the position of his men in the distance in the Shuhada neighborhood.

“See the communications tower,” he said. “They are there.”

The sound of machine-gun fire and explosions rang out. The Special Forces fighters from the police and counterterrorism units had reached Street 40, about two miles from the city’s center on the southern side, he said.

On Saturday, the Iraqi army also announced that it had recaptured two neighborhoods east of the city.

“It’s considered symbolic for ISIS,” Saedi said.

“It was the first city that fought against the Americans, and extremist Muslims have made it their shrine.”

Nearly 100 U.S. Marines died and hundreds were wounded in a six-week battle for the city 12 years ago, their bloodiest fight of the Iraq War.

“We want to show the Americans we are able to do it, but with their support, of course,” he said.

ISIS has built an extensive network of tunnels to hide from the strikes. Meanwhile, its fighters set fires to obscure their positions from the jets overhead.

“The tunnels go right through the city,” said Brig. Gen. Ali Jamil of Iraq’s counterterrorism forces.

“They use them for transportation, away from the airstrikes, but also to ambush our forces,” he said.

The warrens of tunnels have rooms and lighting, Jamil said. One that was recently discovered stretched for about a half-mile.

The Iraqi forces do not know how far others they have found extend because they blow up the entrances so the tunnels can’t be used.