Two U.S. helicopters that made emergency landings were hit by fire from insurgents, a military official said Monday, while a persistent campaign of roadside bombings injured an American-led coalition soldier and three servicemen in Afghanistan's fledgling army.

Five U.S. soldiers and an Afghan army soldier were injured when the helicopters, both involved in the same combat operation in a rugged part of southern Afghanistan plagued by rebel attacks, made emergency landings Sunday — one north of the former Taliban stronghold of Kandahar province and one in neighboring Uruzgan province.

"Both helicopters received enemy fire," said Lt. Col. Laurent Fox, a spokesman for the U.S.-led coalition force in Afghanistan.

Fox told a news conference it was apparently the enemy fire that forced the two CH-47 Chinooks to make "hard landings," in one case probably damaging the craft beyond repair.

He said the pilots saved lives by landing the helicopters after taking fire and that all six injured soldiers have returned to duty.

The helicopter that landed north of Kandahar province, injuring the five U.S. soldiers, was severely damaged, he said. The other one made it to a forward base and can probably fly again.

An unknown number of militants were killed during the combat operation, Fox said. He said it was unclear what kind of ammunition hit the helicopters.

A purported Taliban spokesman, Qari Mohammed Yousaf, claimed Sunday that the Taliban shot down a U.S. helicopter north of Kandahar with a rocket, but he also claimed all aboard were killed. Yousaf often calls news organizations to claim responsibility for attacks, often with information that proves exaggerated or untrue. His ties to the Taliban leadership are unclear.

In June, suspected insurgents shot down a U.S. special forces Chinook in the east, near the Pakistani border, and 16 aboard were killed.

All five U.S. crew members died when a CH-47 crashed in September in the south, near where Sunday's landings took place, but the military said there was no sign it had been shot down.

The U.S.-backed Afghan government's army and some 20,000 coalition troops are fighting Taliban-led insurgents in southern and eastern Afghanistan. Nearly 1,500 people have been killed this year in the deadliest militant violence since American-led forces ousted the hard-line Taliban from power in 2001.

The persistent violence has hobbled the country's efforts to recover from a quarter-century of war.

On Monday, the explosion of a homemade bomb injured a coalition soldier in the Zabul province, coalition spokesman Lt. Mike Cody said, while provincial government spokesman Ali Khail said a mine apparently planted by militants wounded three Afghan soldiers. Zabul is adjacent to both Kandahar and Uruzgan provinces.

On Sunday, three U.S. soldiers were injured when a homemade bomb detonated near their convoy during combat operations in Zabul province, and a Canadian coalition soldier was slightly injured in an explosion in the city of Kandahar that killed the attacker and a civilian, officials said.

Since Friday, Afghan police and coalition forces have broken up two operations where militants assembled and planted roadside bombs, arresting five people in raids in the Ghazni province, southwest of Kabul, and near the main U.S. base at Bagram, north of the capital, U.S. military spokesman Lt. Col. Jerry O'Hara said.