Qawalish, Libya (CNN) -- The front lines of Libya's grinding war weave through the western mountains and around Zlitan, the last city east of Tripoli still under the grip of strongman Moammar Gadhafi.

In many places that Gadhafi's forces have fled, they've left behind deadly fields of mines -- tens, perhaps hundreds of thousands of them, say the rebels.

Not only do they pose a danger for civilians but they also have slowed the advance of the rebels in their march toward Tripoli.

Here in Qawalish, a town 60 miles southwest of Tripoli where fierce fighting has taken place in recent weeks, the war looks like this: Men in no protective gear sift through a public park to fight an enemy that can kill instantly and indiscriminately. Here, the enemy is Gadhafi's landmines.

Milad al Saidy and his fellow "sappers," as those who work with mines are known, are armed only with simple metal probes and a couple of metal detectors. A burned-out shell of a car sits as evidence of what the mines can do.

So far, they say, about 2,500 mines have been discovered, all left by fleeing pro-Gadhafi forces.

Al Saidy has been doing this work for 16 years but many others are green -- fresh recruits who volunteered for a potentially deadly job. Some learn on the job. Amazingly, al Saidy said, no one has been killed or hurt.

"It's very, very dangerous but people are insisting they want to work with us to secure the lives of the innocent, the children, so families can come without the fear of landmines," he said.

The sapper teams find a Chinese-made anti-tank mine, designed to blow up armored vehicles. The rebels explain that the anti-tank mines require a lot of pressure to detonate.

So, Gadhafi's men place Brazilian-made anti-personnel mines, which blow when a person steps on them, atop the bigger mines. The result is an easier but potentially far more deadly blast.

The work, al Saidy said, is crucial. He and his men toil under the sun, even though it is Ramadan. They observe the rules of the holy month, neither eating nor drinking and pausing only to pray.

"The circumstances command us to work," he said.

Farther west, rebel fighters loom over the town of Tiji from an observation post.

This place, the locals say, was used by the Berbers 2,000 years ago to look out for invading Roman armies. Now it's a lookout for a whole new war.

The rebels call Tiji a gateway city. If they are able to wrest control from Gadhafi's men, there would be little between them and Tripoli. But talk of victory and actually achieving it are two different things.

The rebels said they engaged Gadhafi's troops this week but then saw women and children running into houses. So they stopped.

"In this situation we're facing a big problem because Gadhafi is using people as a human shield," said Tarek Zambou, head of the local military council.

CNN could not independently verify that claim, but it's clear that after making significant gains last week in half a dozen towns beneath the Nafusa Mountains, rebel advances have stalled in this key town.

The rebels said they have sent word to residents: Leave now. It won't be long before they are firing again.

Five months into the Libyan war, the rebels have won international support and NATO jets have continuously bombed Gadhafi's forces. But so far, they have not been able to break the dictator's hold.

On the eastern front, they have been pushing in Zlitan. Thursday, however, it appeared that Gadhafi's forces were still in control of the central city.

In recent weeks, NATO has intensified its bombing of Zlitan, which is less than 50 miles west of rebel-held Misrata. Tuesday, jets struck two buildings in Zlitan, the alliance said. One of Gadhafi's main battle tanks was destroyed in that attack.

A follow-up run Thursday morning attacked another command-and-control center, used to support multiple rocket launchers, NATO said.

A mother and her two boys were buried Thursday. The Libyan government, which took reporters on a tour of the city, said they were killed in the airstrikes that hit a two-story villa in a residential neighborhood.

A NATO spokesman acknowledged the airstrike but said: "We do not know of any casualties, we have only heard the government allegations of casualties visa the media."

Abu Bakr, the brother of the slain woman, wept through the funeral. He pulled back the blankets covering the two small coffins bearing the bloody bodies of his nephews, Mohamed, 5, and Motez, 3.

"Whether you like it or not, we're staying here," he yelled. "This is our country."

He damned NATO and "the rats," the Libyan regime's word for the rebels.

Back in Qawalish, al Saidy, the sapper, leaves the minefields to return to his vehicle. He knows there is no end date yet for his risky work.

"The more we advance, the more landmines we are facing," he said.

But at least on this day, there's good news. No new mines.

CNN's Michael Holmes reported from Qawalish and Tiji and Ivan Watson reported from Zlitan. Jomana Karadsheh contributed to this report.