Kabul, Afghanistan ? Militants hiding in a vineyard and armed with machine guns ambushed an Afghan army convoy Saturday, shooting dead four soldiers but losing 15 of their own. Violence elsewhere killed another 15 people, including two French troops and a U.S. soldier.

The 34 deaths came amid some of the worst fighting in Afghanistan since the ouster of the Taliban in 2001 and reinforced fears of a resurgence of Islamic extremists.

About 120 people were killed during a 24-hour spasm of violence earlier this week, before calming briefly. It erupted again Friday with six militants, an Afghan soldier and a civilian killed in Helmand province, the main opium poppy-growing region, where drug profits are believed to fund the insurgency, said Gen. Rehmatullah Raufi, military commander for the south.

The U.S. soldier was killed Friday in Uruzgan province, also in the south, the military said in a statement. Six soldiers were wounded and in stable condition.

At least 235 members of the U.S. military have died in and around Afghanistan as a result of the U.S. invasion of Afghanistan in late 2001, according to the U.S. Defense Department.