Israel is responding with force to take out what it calls threats to its security.
CBN News has previously covered the story of the tunnels used to smuggle weapons and supplies into Gaza. On Tuesday, the Israeli Air Force bombed several of those tunnels.
Israel said the strike was retaliation for Palestinian militants firing mortars into southern Israel.
Palestinian rescue teams armed with a bulldozer rushed to the scene Tuesday morning searching for survivors.
Three Palestinians were killed and six others are missing after an Israeli plane hit a smuggling tunnel in Rafah, southern Gaza, just one of several sites completely leveled.
"The reason for the air strikes, like the one (Tuesday) morning, are the continuing rocket and mortar attacks," explained CBN News Jerusalem Bureau Chief Chris Mitchell. "Since the end of Israel's Operation Cast Lead earlier this year, Palestinians have fired more than 200 rockets into southern Israel. If the rockets would stop so would the air strikes."
CBN News was recently granted an exclusive look inside these tunnels.
Because of an Egyptian and Israeli blockade of Gaza, smugglers use the tunnels to ferry everything from gas to livestock, clothes and food.
Israelis argue that the tunnels are also used by Hamas to smuggle in weapons. Despite Israel's attempts earlier this year to destroy them, business is booming again inside these tunnels.
"The tunnel industry is reviving again," said Israeli Army spokesman Avital Leibovich. "Since they begin to smuggle regular explosives through, this means a whole new game."
CBN News found young Palestinian tunnel diggers working around the clock to ferry supplies.
"I am making $12.50 per day," one worker said. "I would rather die than seeing my kids with no food. I have 10 kids."
It is the large amounts of weapons, like rocket-propelled grenades, explosives, AK-47s, bullets and other types of ammunition moving into the Gaza strip through the tunnels that worry the Israelis the most.
"Before Hamas came to power three to four tons of explosives have been smuggled through these tunnels," Leibovich added. "After Hamas came to power, we are talking at least about hundreds of tons of explosives were smuggled inside Gaza every year."
A tunnel can be up to 15 meters deep and run for 250 meters. It usually takes about eight weeks of non-stop digging and drilling to complete one tunnel.
The Israeli Army estimates there are now some 300 tunnels along the Gaza-Egypt border.