Israel carried out 40 airstrikes Wednesday on targets including smuggling tunnels on the Gaza-Egypt border, Israel's chief army spokesman Brig. Gen. Avi Benayahu said.

An Israeli combat officer, identified as Lt. Col. Amir, said troops neutralized hundreds of explosives devices, including booby-trapped houses.

Residents said 16 houses on the border were destroyed, with Israel presumably targeting buildings shielding tunnel entrances. Hamas had about 300 smuggling tunnels in the area before the offensive, and Israel has already destroyed dozens in repeated strikes.

Fida Kishta, an area resident, said she could hear sporadic shelling from F-16 planes.

"I feel like the ground is shaking when we hear the shelling. People are terrified," Kishta said.

In the evening, an Israeli warplane dropped leaflets over the Rafah refugee camp on the Gaza-Egypt border, urging residents to flee because of planned Israel strikes. Hamas has weapons smuggling tunnels in the area, and Israel has already destroyed dozens of them in airstrikes.

"Because Hamas uses your houses to hide and smuggle military weapons, the IDF will attack the area, between the Egyptian border until the beach road," the leaflet said, according a local U.N. official.

After the leaflets were dropped, about 5,000 fled to two U.N. schools turned into temporary shelters.

Despite the army's push, Gaza militants fired 14 rockets Wednesday, including hits on the cities of Beersheba and Ashkelon.

Rocket fire has fallen off somewhat as Israeli troops tighten their hold on Gaza, taking over open areas used to launch rockets, but Gaza residents say militants are still launching from heavily populated areas.