Upper Manggas, Philippines ? Green Berets sped into a combat zone in a pickup truck Tuesday to help Filipino soldiers to safety after rebels unleashed grenades and small-arms fire on a Filipino army patrol.

It was the second time U.S. troops have ventured into the combat zone since February, when they began advising the Philippine army in its fight against Abu Sayyaf rebels. Abu Sayyaf is believed to have links to Osama bin Laden’s al-Qaida terrorist network.

The clash Tuesday between about 30 Filipino troops and a group of Abu Sayyaf fighters erupted within earshot of the Green Berets as they attended a town meeting on the southern island of Basilan to discuss residents’ safety concerns.

At least four rebels were killed in several hours of fighting on the outskirts of the town of Lantawan, officials said. Elite Philippine troops captured six more rebels as they fled the fighting.

After a series of frantic radio calls, the four Green Berets learned that Filipino platoon commander Lt. Lemuel Beduya had a serious head wound and that one of his men was shot in the arm. Both were pinned down by enemy fire about two miles from where the Americans were meeting residents in the village of Atong Atong.

As the fight raged, the elite U.S. troops piled into a blue pickup truck and headed out to evacuate the wounded Philippine soldiers. They were joined by government soldiers in another truck and an armored personnel carrier.

Heavy fighting blocked the initial rescue effort, but the two wounded Filipinos later were brought to the safety of a helicopter landing zone by other Filipino soldiers, where they were rescued by the Green Berets.

About 160 U.S. Special Forces members and 500 other American personnel are in the southern Philippines to train Filipino soldiers battling the rebels, who hold hostage Wichita, Kan., missionaries Martin and Gracia Burnham and Filipina nurse Ediborah Yap.

The U.S. soldiers are armed but can only fire in self-defense. The Special Forces members on Basilan must always stay with local Filipino commanders.