Four gunmen on motorcycles ambushed a U.S. military reconnaissance patrol in southern Afghanistan today, killing two Americans and wounding a third, officials said. Three Afghan soldiers also were wounded.

The deaths in Helmand province were the first fatalities among U.S. forces in this country since December. But they came just two days after a Red Cross worker was killed in southern Afghanistan in what could signal a resurgence of activity by anti-U.S. forces in connection with the start of the war in Iraq.

Meanwhile, U.S. Special Operations soldiers backed by air support joined about 1,000 Afghan troops in Uruzgan province to battle about 100 fighters loyal to the former Taliban administration, the U.S. military said. At least 15 fighters on the Taliban side were reported killed.

In recent interviews, Taliban loyalists hiding in neighboring Pakistan said that training camps had been established in the Afghan mountains and that anti-American forces, which also include members of Osama bin Laden's al Qaeda network and the private army of renegade commander Gulbuddin Hekmatyar, had united. In the interviews, the Taliban loyalists warned of stepped-up attacks once the war in Iraq began.

One U.S. Special Forces soldier and an airman were killed and another Special Forces soldier was wounded when their four-vehicle convoy was ambushed during a reconnaissance patrol near the town of Geresk, the military said in a statement from Bagram air base, headquarters of U.S. forces.

The Pentagon identified one of the slain Americans as Staff Sgt. Jacob L. Frazier, 24, of St. Charles, Ill., who was assigned to the 169th Air Support Operations Squadron, 182nd Airlift Wing. The other casualties were not immediately named.

Col. Roger King, an Army spokesman, said there were fewer than 20 people in the convoy. "They drove into a kill zone," King said. The convoy sped out of the area after the Americans were shot and a gunfight ensued, he said.

There likely will be a response from the U.S. military, which recently finished an anti-terror sweep known as Operation Viper in the area. "We'll probably make attempts to find out who did the ambushing," King said, without elaborating.

Today's deaths bring to 18 the number of U.S. soldiers killed in combat in Afghanistan.

Dad Mohammed Khan, intelligence chief of Helmand province, said the U.S. soldiers were inspecting a school and hospital built with U.S. funding when they were ambushed by four men riding two motorcycles. The gunmen escaped. He identified them as Taliban fighters, but he did not reveal the source of his information.

The surge in violence in the south has disrupted some international aid projects in Afghanistan.

The Geneva-based International Committee of the Red Cross, which has 160 foreigners and 1,500 Afghans working in this country, said it was suspending operations after Wednesday's killing of Ricardo Munguia, 39, a citizen of El Salvador and Switzerland.

Munguia, a water engineer, was intercepted on a dirt road while driving back to Kandahar from a project in Tirin Kot, about 70 miles to the north.

No coalition casualties were reported in the battle in the Khakrez district of Uruzgan, a southern province, but six Afghan soldiers were wounded, authorities said.

In Oslo, the Norwegian military said two Norwegian F-16 jets on a routine patrol were called in to support coalition ground troops and dropped four laser-guided bombs on targets northeast of Kandahar.