(Adds air strike, updates casualties)

KFAR AZA, Israel, May 9 (Reuters) - A Palestinian mortar attack from the Hamas-controlled Gaza Strip killed an Israeli civilian on Friday, a police spokesman and ambulance workers said.

After the mortar attack, two Israeli air strikes killed five Hamas security men in the Gaza Strip, Palestinian medical officials and Hamas said.

Palestinian militants from the Islamist group Hamas, who regularly fire rockets and mortars into Israel from Gaza, claimed responsibility for the attack on the Kfar Aza collective farm in southern Israel.

Such attacks rarely cause death or injury but sow panic in border towns. Ambulance workers said the dead Israeli civilian was a middle-aged man and three other people were wounded.

The last time an Israeli civilian was killed by cross-border fire, on Feb. 27, the attack was followed by days of Israeli military action in the Gaza Strip which left more than 120 Palestinians dead. Many of them were civilians.

Palestinian medical workers said four other Hamas security men were wounded in the Israeli air strikes on Hamas outposts in the southern Gaza towns of Rafah and Khan Younis.

An Israeli army spokeswoman said the air strikes were in response to continued cross-border attacks.

Israel frequently conducts raids in Gaza which it says are aimed at curbing the rocket fire. More than 1,950 rockets and mortars have been fired from Gaza at Israel this year, the army said.

Separately, a Palestinian gunman was killed in a clash with Israelis in the occupied West Bank on Friday, Palestinian security sources and Israeli emergency workers said.

Israeli and Palestinian sources offered differing accounts of the incident near the West Bank city of Ramallah.

Palestinian security sources said the gunman was killed by Israeli soldiers.

Israel's ZAKA emergency service said the gunman was killed by armed Israeli settlers who had come under attack.

The Israeli army said it was investigating the incident. (Reporting by Yehuda Peretz and Nidal al-Mughrabi in Gaza; editing by Andrew Roche)

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