Six body bags lay next to three children's bicycles in the kibbutz of Kfar Aza Tuesday where Israeli forces said Hamas fighters massacred more than 100 civilians during the weekend's shock assault.

When the Palestinian militants stormed the kibbutz, they "set fire" to several homes in what had been a bustling community "to force their occupants to come out", said Omar Barak, a 24-year-old Israeli officer.

"But many preferred to die in the fires ... than be killed by the terrorists," he said of the wave of Hamas fighters who infiltrated southern Israeli communities from the Gaza Strip in a pre-dawn attack on Saturday.

"We have found many bodies inside the homes," he added.

The farming community is located just two kilometres (about a mile) from Gaza which Israel bombarded relentlessly on Tuesday in retaliation for the worst attack on its territory in decades.

Hamas militants killed some 900 people in Israel, shooting dead hundreds of civilians including at a desert festival and dragging 150 hostages back to Gaza.

In retaliation, Israel has bombarded Gaza also leaving 900 dead and Israeli officials said they found 1,500 bodies of militant fighters in the south.

Barak was among the Israeli forces who fought the assailants for two long days to take back control of Kfar Aza.

"I had never seen anything worse. I broke down when I saw the bodies of two children assassinated," he said.

Retired Israeli major general Itai Veruv said he had been in shock seeing "all the bodies of the civilians ... the dead children," adding it was "a big massacre, a big disaster."

Residents of Kfar Aza were used to tensions and violence involving Palestinians, but chose to live close to the blockaded Gaza Strip.

Some believed they had to maintain an Israeli presence near the coastal enclave, even after Israel withdrew its troops from there in 2005, while others had made their homes there because it was cheaper than elsewhere in Israel.

- 'Wave after wave of fighters' -

The bodies of Palestinian assailants were sprawled on the ground of the kibbutz Tuesday, some still wearing their thin black bullet-proof vests.

A smell of death permeated the air.

According to Veruv, Israeli forces fought "wave after wave of Hamas terrorists" in Kfar Aza.

There were "70 terrorists fully armed, fully skilled," he said.

"In 40 years of service I saw many difficult things, but never something like this," Veruv added.

About 400 people lived in Kfar Aza, where several Israeli soldiers questioned by AFP said more than 100 civilians had been killed. Some even advanced the figure of 150.

In one part of the kibbutz, where residents had kept the lawns tidy outside their modest homes, lay the ruins of a motorised glider used by the militants.

Residents' belongings lay scattered on the ground, including a damaged scooter, a destroyed truck near a grain silo and a pink helmet.

A businessman from Tel Aviv and army reservist who declined to be named said he came to help the Israeli forces battle the militants and regain control of communities around Gaza.

"All I want is peace. It is the only solution... but you cannot have peace with Hamas," after what happened, he added.

Veruv, the retired officer said: "Now it is time to fight, and we will fight for a long time."