KABUL, Afghanistan - A roadside bomb explosion in southern Afghanistan today killed two U.S. soldiers and wounded two, the military said.

The soldiers were traveling in an armored vehicle north of Kandahar, part of a convoy supporting a road construction project, the military said in a statement.

The two wounded soldiers were evacuated to Kandahar Airfield for medical treatment. Both were in stable condition, the statement said.

"These terrorists are attacking the very forces working to improve Afghanistan," said Brig. Gen. Jack Sterling, a deputy commander of the U.S.-led coalition. "It's unconscionable that the Taliban would do something like this. They only offer death and continued suffering to the people of Afghanistan."

The deaths bring to 182 the number of U.S. service members killed in and around Afghanistan since the start of Operation Enduring Freedom in 2001.

BAGHDAD, Iraq - Four U.S. soldiers were killed today by a roadside bomb in the tense, religiously mixed Iraqi city of Samarra, the U.S. military said.Samarra is among a series of towns and cities in central and western Iraq which fell into insurgent hands last year after the United States transferred sovereignty to the Iraqis. U.S. forces regained control last year but the situation there remains uncertain.

COLOGNE, Germany - Hundreds of thousands of young people from around the world jammed into the western German city of Cologne today for the Roman Catholic Church's 20th World Youth Day, singing and praying together as they awaited the arrival of Pope Benedict XVI.About 325,000 flag-waving and hymn-singing pilgrims had arrived by Wednesday, organizers said, with up to a million people from 184 countries expected by the time Benedict celebrates a closing Mass on Sunday.Most have known only one pope - the charismatic John Paul II, who died April 2 after serving 27 years - and were curious to see how his successor, a former theology professor and Vatican doctrine official elected April 19, would connect with the faithful. Many made their plans to come while John Paul was still alive and had hoped to see him.