An Israeli man was killed and four other people were wounded on Thursday when Palestinian militants in the Gaza Strip fired a mortar shell into Kibbutz Nir Oz in the western Negev.

The fatality was named as Amnon Rosenberg, 51, a father of three from nearby Kibbutz Nirim. He was killed when the shell hit outside the paint factory at Kibbutz Nir Oz.

Three of the casualties were moderately wounded and the fourth sustained minor wounds in the strike. All the victims were hit with shrapnel from the shell.

Not long after the mortar shell strike, Palestinian doctors said a 4-year-old girl was killed and her mother wounded by an Israel Air Force attack on the Gaza Strip.

Hamas security said the Israeli aircraft targeted a group of militants in the southern Gaza Strip but missed them. Relatives of the girl said that she and her mother were in the yard of a house that was hit by the errant missile.

After the mortar shell hit Gaza, it emerged that the "Color Red" early warning system did not sound prior to the attack, and that the casualties were inside an unprotected building.

Magen David Adom emergency medical personnel said one of the victims was already dead when they arrived at the scene, and three other people had suffered shrapnel wounds to the chest and abdomen. One person was lightly hurt and was later treated for shock.

The militant Palestinian group Hamas claimed responsibility for the attack. Since Hamas seized control of Gaza a year ago, Palestinian militants have fired rockets into Israel almost daily. Israel frequently responds with air strikes and ground incursions into Gaza.

"We will confront the occupier with all our means and we will continue striking the Zionist military sites and settlements around Gaza in response to the continued aggression against our people," Hamas said in a statement.

Spokesman for the Prime Minister's Office, David Baker, blamed Hamas for the attack and said it would be held accountable for salvoes into southern Israel.

"Israel cannot and will not allow the situation to continue," Baker said.

Kibbutz Nirim published an obituary of Rosenberg, saying: "Today we lost a friend who was always happy to help others. Solidarity was of paramount importance to him, and he labored to pursue it in practice."

"We witnessed a tragic proof of the dangers inflicted by the ongoing absence of security measures. We urge the government to help us continue to live safely in the region," the Kibbutz statement said.

Egypt has been trying to mediate a cease-fire between Hamas and Israel and Thursday's attack is likely to complicate those efforts.

On Tuesday, seven Qassam rockets and four mortar shells hit the western Negev, with five rockets striking the Eshkol region in the western Negev. Five people were wounded in the rocket salvo, including two Bedouin workers who were in the field, a farmer in the Yesha community and two migrant workers from Thailand.

One of the Thai workers suffered moderate wounds to the head, and the other was lightly hurt. The Thai embassy issued a statement on Wednesday, saying "The government is concerned over the welfare of its citizens working in Israel. The Thai workers come to earn money and support their families in Thailand, and now the situation has become more dangerous for them."