Transcript for Battleground Gaza: Israeli-Hamas Conflict From Both Sides
As this -- at this hour as dawn breaks in the holy land, people on both sides are bracing for what has quickly become one of the longest and deadliest war between the Palestinians and Israelis. Two teams on the front lines, giving unprecedented access to a thank Y thank yank unit. Reporter: As they gather, we're going in today with the soldiers of the 188th armored brigade, suiting up. But in moments, alert, in-coming mortar fire, and we run for shelter. Clear? All clear. Said to wait for ten minutes, no one actually does that. Reporter: Back to work, these soldiers are preparing to go back to battle. Their leader knows the dangers and the costs of this operation. You came under fire? Yes. My driver was killed. And another officer. Reporter: But the colonel and his troops remain determined and proud in their work. How is this morale among your guys? The morale is very high, every guy in the brigade has a family. The sergeant is honest. Are you scared going in? Of course. Reporter: Inside it is a rough ride, very hot, choking with exhaust fumes. We cross into gaza, hamas territory, the gunner anxiously scanning the dusty roads and deserted buildings. The mission today, find and destroy hamas-built tunnels. They are a terrifying threat to ordinary Israelis, 36 tunnels uncovered so far. Palestinian fighters have infiltrated Israel several times, Monday killing five soldiers before slipping back across the border. Several miles into gaza, our convoy stops. A tunnel dug up and exposed, soldiers standing guard. This tunnel was found this morning by the Israelis. They say it leads about 400 yards where there is another entrance under a house and they believe this tunnel goes under the border, under the fence into Israel. But they are not going in. The assumption is it is booby-trapped. This is the difference between us and hamas, the hamas looks to kill innocent civilians. We do anything to avoid killing innocent civilians. Reporter: But for the people of gaza, that is hard to believe. Israeli artillery shelling a U.N. School, doubling as a refugee camp. Hellish and tragic scenes. ABC's David Wright is on the front lines on that side in northern gaza where it already is turning out to be a horrible day. One of the shells struck this classroom where mothers were sleeping with their children, thinking that this of all places was safe. Because look up. There is the U.N. Flag. But that didn't protect them. Witnesses say they heard several explos rounds. Two here and one here. Reporter: In the roof and in the classroom walls, holes from the artillery shells, killing 17 people, injuring dozens more. It is just awful. This is criminal. Reporter: He is normally a math teacher. Now he is helping to run this refugee camp, one of more than 80 U.N. Schools across gaza. The U.N. Says it communicated the coordinates of this camp 17 separate times to the Israeli military, including just last night. No official response yet from Israel. But the Israeli military is investigating. Many of the people here fled the nearby U.N. School that was attacked just last week. A tailor is here with 19 members of his family. I have never seen anything like it, he told me, describing the terrible scene, he tells me these families were slaughtered in their sleep. The place that I left, he says, I even more dangerous. The sad fact is, there is no place else to go. The soldiers of the Israeli defense forces, proud soldiers, what did they feel when they see the innocent dead, the broken bodies of so many children? Everyone where in the world, no matter, their race, their religion. A child is a child. Reporter: But it is a murky battlefield, densely populated. And Israel has seen ferocius criticism. People say you are brutalizing the people. What would you say to them? We do everything we can to not harm innocent people. Reporter: Suddenly, sniper fire, the Israelis engage the threat. We hunker down for several minutes. So the Israelis are trying to put down fire, suppressing the fire action that is holding us here. The Israelis lay down a smoke screen, and we use it as cover to return to the vehicle. Back across the border, to Israel. It's just before sunset now, and the humanitarian cease-fire appears to be over. We're told an explosion has happened. At least 17 people killed, possibly 200 injured. Late afternoon, the second mass casualty event of this day. One of the most crowded markets in gaza hit according to eyewitness's by an air strike in the run-up to dinner. These are cell phone images of the immediate aftermath. Much of it too gruesome to show. Hamas is calling this incident a massacre. You can see the blood on the ground here and off in the distance is the sound of incoming fire. Once the shelling starts no place feels totally safe. We're having to drive fast now because there were also reports that three Israeli soldiers were killed and Israel is expected to retaliate hard tonight. But on the way home one more quick start. It is almost sunset now and I count one, two, three funerals going on. People who have just died. Just killed in the marketplace. Three, they had no idea that their day would end here in the graveyard, but tonight they're burying their family members. As night falls, both sides dig in for the fight with no end in sight. Millions of people on both sides caught in the cross fire. Our profound thanks to David Wright and terry Moran.
This transcript has been automatically generated and may not be 100% accurate.