A gunman who infiltrated from Egypt sprayed four Israeli vehicles with assault rifle fire Sunday, killing four people and wounding 24, the army said. The army said the lone gunman killed three Israeli army soldiers and a civilian driver for the national Egged bus company on the Israeli-Egyptian border, about 15 miles northwest of the Israeli Red Sea resort of Eilat. The gunman escaped back into Egypt. A senior Egyptian security source said an Egyptian border policeman assigned to the area of the attack had been arrested as the suspected assailant. Earlier reports from Cairo said the gunman had fired from the Egyptian side of the border. In Amman, Jordan a fundamentalist Islamic group Sunday claimed responsibility for the attack. The extremist Islamic Jihad-Beit Al-Maqdes, or Islamic Holy War-Jersualem, said the attack was carried out by ``one of our units operating in the land of Arabism and Islam, the land of Egypt.'' Defense Minister Moshe Arens called the attack ``a most serious incident'' and said Israel expected Egypt to take all the necessary steps to prevent such assaults. A military commander identified only as Brig. Gen. D. said on army radio that an Egyptian man ``whose identity is not clear to us at this moment'' infiltrated into Israel at the distance of about 300 yards from the scene of the shooting. ``He entered a dry riverbed, reached the road and lay in wait on the roadside,'' the commander said. The assailant opened fire on an army van, containing just the driver, who was injured but carried on for a few hundred yards and stopped. Another military car, also containing only one person and heading from Eilat to a nearby base, was hit by several bullets. The soldier inside was mortally wounded, drove for a few hundred yards and died, the commander said. Next came a military bus. The driver thought there had been an accident and stopped. He got out with his weapon but was shot dead ``at very close range'' before he could fire back. Finally, the attacker fired on an Egged bus carrying civilians working at military installations in the area. He wounded a security guard, who shot back, hitting the assailant. ``We found signs of blood showing that he was hit. I think this prevented a heavier tragedy,'' the commander said. ``The terrorist apparently intended to board the bus and take it over. He (the guard) did not let him come on board. He climbed down through the door and shot him, and from that moment the terrorist began running away.'' Reporters at the scene saw a red and white passenger bus with its windshield covered with bullet holes. Police forensic experts were seen picking up bullets around the bus. Isaac Bar-Moshe, press officer at the Israeli Embassy in Cairo, said the gunman had used a Soviet-made Kalashnikov semiautomatic rifle. If the attack was indeed committed by a member of Egypt's uniformed forces, it would be the second. On Oct. 5, 1985, an Egyptian border police officer went berserk and shot dead four Israeli children, two women and an elderly man near the border in the Sinai Desert. Before Sunday, the latest attack on an Israeli target in Egypt was on Feb. 4, when gunmen ambushed a tour bus, killing nine Israeli vacationers. The attack took place on a desert road between Cairo and the Suez Canal city of Ismailiya. Egypt is the only Arab state to have a peace treaty with Israel. After the treaty was signed in 1979, Israel began withdrawing from the Egyptian Sinai peninsula, which it occupied in 1967. Between 1984 and 1987, two Israeli diplomats and six Israelis were wounded in Cairo in a number of attacks claimed by an Egyptian terrorist organization, Egypt's Revolution.