By Nidal al-Mughrabi
GAZA, May 15 (Reuters) - At least 11 Palestinians were killed on Tuesday -- eight in one incident -- in the deadliest fighting between Hamas and Fatah since the rivals formed a unity government to end bloodshed threatening to spill into civil war.
For many Palestinians, the violence in Gaza was particularly disturbing, coming on the "Nakba", an annual day of national reflection over shared suffering in the conflict with Israel.
A Palestinian official said Egypt was in "high-level contact" with the feuding factions to try to restore calm.
In an attack near Karni Crossing, Gaza's vital main commercial entry point into Israel, a Fatah spokesman said Hamas gunmen had killed eight members of Mahmoud Abbas's Presidential Guard in cold blood.
The Fatah-affiliated guardsmen were en route to help comrades under assault by Hamas at a training base near the crossing when Israeli forces across the frontier opened fire at them, according to the spokesman, Tawfiq Abu Khoussa.
"Some of the vehicles overturned and some of the men were wounded. The forces retreated but they were ambushed by Hamas gunmen, who finished them off," he said.
In a Gaza hospital, an unidentified Fatah security man who said he had been wounded in the incident told Palestinian television: "They came and shot the wounded. They left me, believing I was dead."
Hamas's armed wing denied the allegation, blaming the deaths on Israel and accusing Fatah of killing one of its commanders earlier on Tuesday. The Israeli military said it had fired at two gunmen who approached the border fence, hitting one of them.
However, Israeli Defence Minister Amir Peretz said Israel had no intention of intervening in the internal fighting.
The Islamist Hamas and the secular Fatah formed a unity government two months ago in a Saudi-brokered deal that failed to resolve the crucial issue of control over security forces, and left armed groups fighting turf wars that have become even more deadly.
"We hoped that our fears would vanish after the unity government was created. I guess we are wrong. We are getting closer to civil war today," said Gaza resident Nabil Zaki, 32.
GUNMEN RULE
A truce announced late on Monday never took hold, and at least 20 people have been killed in internal Palestinian violence since Friday.
Masked gunmen were in control of Gaza's streets, where a pro-Fatah security officer and another man, who was not immediately identified, were killed on Tuesday.
Residents who dared to leave home had to dart across streets, shoulders hunched, to the crackle of gunfire.
Palestinian leaders renewed appeals for calm in speeches marking the annual "Nakba", or what Palestinians describe as the tragedy that befell them when Israel became a state in 1948.
"Today we are witnessing a new Nakba," said Umm Mohammed, 56, a Gaza resident.
In a challenge to Hamas, a 450-strong contingent of Fatah fighters that had been receiving advanced training in Egypt entered the Gaza Strip through the Rafah border crossing with Israeli approval, Western sources said.
The United States has earmarked millions of dollars to provide training and non-lethal equipment to the Presidential Guard, which is widely seen as a counterforce to Hamas gunmen.
(Additional reporting by Mohammed Assadi in Ramallah)