Two IDF soldiers were killed Saturday morning when Hamas terrorists infiltrated Israeli territory via a tunnel under the border fence from the central Gaza Strip and opened fire on a military vehicle that was patrolling on the Israeli side of the border, the IDF said Saturday evening.

The two were named as Amotz Greenberg, 45, a major in the reserves from Hod Hasharon, and Sgt. Adar Barsano, 20, from Nahariya. The information was cleared for publication after the families were informed.

The deaths were the first of soldiers killed by Hamas since Operation Protective Edge began on July 8.

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The terrorist cell infiltrated Israeli territory through a tunnel, in an apparent attempt to carry out a major attack on one of the nearby communities, the army said. The IDF vehicle was not the intended target. Its presence at the scene prevented a much larger planned attack, military sources said late Saturday.

The army believes there are 20 more such tunnels, and that further efforts to infiltrate and kill Israelis are likely. Larger contingents of soldiers were deployed to the Israeli side of the Gaza border area after the incident, military sources said, to guard against further such attacks.

An initial investigation indicated that eight or nine Hamas gunmen clad in IDF uniforms infiltrated beneath the border fence.

The gunmen encountered the IDF patrol and opened fire with machine guns and anti-tank weaponry, killing the two officers, moderately wounding two other soldiers and lightly wounding two others.

Troops returned fire, killing one of the terrorists; others fled back into Gaza.

Military sources said that material found at the scene, including plastic handcuffs, indicated that the terrorists intended to kill and kidnap Israeli civilians and/or soldiers.

Residents in nearby areas, including Kibbutz Ein HaShlosha, were told to stay indoors for several hours while the IDF searched for other gunmen.

The wounded soldiers were evacuated to hospitals, and the families of the dead soldiers notified.

The army said afterwards it had carried out an air strike in Gaza targeting several terrorists involved in the attack, although it was unclear if there were casualties.

The army was investigating why the tunnel was not spotted earlier and the infiltration thwarted.

Hamas’s military wing had said Saturday that a number of highly trained fighters managed to infiltrate Israeli territory and carry out an operation against IDF soldiers near the central Gaza Strip. The group said its fighters had exchanged fire with Israeli troops and caused casualties. It claimed falsely that its gunmen attacked four military vehicles and remained inside Israeli territory for six hours, Israel’s Channel 2 reported.

The two IDF deaths on Saturday, along with that of a civilian killed near Dimona on Saturday, brought the number of Israelis killed in the 12 days of conflict to five — three soldiers and two civilians. (IDF soldier Eitan Barak was killed by errant tank fire overnight Thursday-Friday, the IDF said.)

A second firefight was reported in the north of the Gaza Strip, where soldiers also came under fire, though details remained sparse.

Also Saturday, IDF officials stated that the army was preparing to widen the scope of its ground operations in the Palestinian enclave.

The army added that a task force established specifically in order to address the tunnel threat from Gaza had helped infantry forces detect a total of 13 cross border channels during the first stage of the ground operation, dealing a significant blow to a central component of Hamas infrastructure. The task force was assembled one year ago, combining elements of military intelligence’s Unit 8200, which handles signals intelligence, and the IDF mapping unit, among others, IDF spokesman Lt. Col. Peter Lerner said.

All the tunnels found since the IDF’s ground incursion in the Strip began on Thursday stretch from Gaza to Israeli territory. Lerner said that the entrances on the Palestinian side of the border were located in greenhouses and private homes.

Lerner went on to say that the army had already eliminated close to 3,000 rockets in Gaza. Considering the fact that terrorists in the Strip have fired some 1,100 projectiles, it is estimated that half of the projected 10,000 rockets in the possession of Gaza terror groups have been used or destroyed.

The army stated that it is currently engaged in three main efforts, namely: the aerial assault, the limited ground offensive, and preparations “for expansion of activities.”

As of Saturday, the air force had launched some 2,400 strikes against “terror targets” in the Strip.

IDF officials said around 50,000 Palestinians have left their homes in the Strip following warnings from Israel that army intends to operate against Hamas targets in the areas in which the Gaza residents live. Military officials said that many of the displaced Palestinians have taken shelter in buildings and institutions operated by the UN.

Meanwhile, international efforts to achieve a truce between Israel and Hamas have stepped up over the past few days, as officials in several different countries scurried between meeting rooms in order to negotiate the terms of a possible ceasefire.

On Friday night, Palestinian Authority President Mahmoud Abbas spoke with US Secretary of State John Kerry over the phone and discussed the need to reach a ceasefire as soon as possible. Qatar has formulated a ceasefire proposal that reflects Hamas’s terms.

Abbas said he supported Egypt’s attempts to negotiate a ceasefire between Israel and Hamas – efforts which Israel has endorsed but which have so far been spurned by Hamas.

Mitch Ginsburg and Avi Issacharoff contributed to this report.