Two local Red Cross workers were killed and a third wounded Monday when they came under fire from inside a Palestinian refugee camp where the Lebanese army has been fighting Al Qaeda-inspired militants holed up inside. A Muslim sheik trying to mediate the conflict also was wounded in a separate shooting incident.

Security officials said the workers, identified by the state-run news agency as Boulos Maamari and Haitham Suleiman, were killed near the northern entrance to the Nahr el-Bared camp when their vehicle was struck by what appeared to be a mortar shell fired by Fatah Islam militants from inside the camp. A third Red Cross worker was seriously wounded.

The officials, who spoke on condition of anonymity because they were not allowed to talk to the press, said there also were army casualties from the shelling but did not give more details. Red Cross officials did not immediately respond to repeated requests for comment.

In a separate incident near the camp's southern entrance, a Muslim sheik trying to negotiate an end to the conflict was wounded as he left Nahr el-Bared.

Hospital officials at the Islamic Hospital in the northern city of Tripoli where he was taken said Sheik Mohammed Haj was lightly injured in his leg when the vehicle he was in belonging to the Palestinian Red Crescent came under fire from inside the camp.

Haj's spokesman Sheik Walid Abu Heit told reporters at the hospital that the incident would not stop Haj's mediation efforts. "We do not blame anyone for the incident at this point," he said.

The Red Cross workers' deaths came as Lebanese troops exchanged sporadic gunfire with Fatah Islam on Monday.

A senior military official told The Associated Press Monday that the army would continue to expand its control in and outside the camp with the aim of tightening the noose around Fatah Islam gunmen.

"The battle will continue until the gunmen surrender and those responsible for killing Lebanese soldiers are brought to justice," the official said, speaking on condition of anonymity because he was not authorized to give official statements.

The official said later Monday that troops had made significant advances and were able to destroy the residence and headquarters of Fatah Islam leader Shaker Youssef al-Absi, leveling it to the ground. It was not immediately known where al-Absi was during the attack.

The NNA said the army seized "very important documents" from al-Absi's headquarters. It also said troops repelled an infiltration attempt by Fatah Islam members, killing seven of them. The report could not be immediately verified.

One Lebanese soldier also was killed in the fighting Monday, raising the number of soldiers killed in the Nahr el-Bared fighting since it began on May 20 to 58, the military official said. Another two soldiers were killed in last week's clashes with Jund al-Sham militants in the Palestinian refugee camp of Ein el-Hilweh in southern Lebanon.

More than 130 people in total, including at least 60 Fatah Islam militants, 20 civilians and the two Red Cross workers, have been reported killed in the fighting in northern Lebanon — the worst internal violence to engulf the trouble-plagued country since the 1975-90 civil war.

In a sign of continued tension outside the camp, Lebanese policemen found a hand grenade on Monday near the house of former Justice Minister Joseph Shaoul in the Christian neighborhood of Ashrafieh in the heart of Beirut, security officials said, speaking on customary condition of anonymity. Security forces blocked the road as a military bomb expert safely removed the grenade, which did not explode.

Fears of spreading chaos have also been sparked by clashes at another Palestinian refugee camp, Ein el-Hilweh in the south, and several bombings in the Beirut area.

Meanwhile, Lebanese security forces arrested four Lebanese men Monday suspected of belonging to a militant Islamic group during raids on their houses in southeastern Lebanon, security officials said. It was not immediately known if the four belonged to Fatah Islam.

Last week, state security officers captured three foreign militants — two Syrians and an Iraqi — during a raid on their house in eastern Lebanon who confessed to belonging to al-Qaida and planning to stage attacks with car bombs, the state-run National News Agency said.

A Lebanese military magistrate also has filed terrorism charges against 27 suspected members of Fatah Islam.