A U.S. paratrooper was killed Saturday after his patrol came under fire in a volatile province near the eastern border with Pakistan and a British soldier was shot to death in northern Afghanistan. Officials said at least 21 other people were killed in fighting last week.

The fighting in southern and eastern Afghanistan (search) was the deadliest in recent weeks and comes a month after landmark legislative elections that many people had hoped would sideline the insurgents.

Violence also broke out in northern Afghanistan, which has been spared much of the bloodshed suffered in other areas, on Saturday when gunmen fired at a patrol of British peacekeepers in Mazar-e-Sharif (search) city, said Sheir Jan Durani, a police spokesman.

Britain's Ministry of Defense said a British soldier had been killed and five wounded in the shooting in Mazar-e-Sharif. Security forces cordoned off the area and arrested four suspects.

A defense ministry spokesman in London, speaking on condition of anonymity in line with government policy, said the troops had been moving between two bases in Mazar-e-Sharif when they came under attack.

Police and peacekeepers in Kabul discovered a large weapons cache hidden in an old building, including rocket-propelled grenades, anti-tank missiles, bombs and ammunition, according to a statement by the NATO (search) force.

The U.S. patrol came under fire in Khost province and American forces responded with small-arms fire, artillery and air attacks, prompting the militants to flee. It was not immediately known if any militants died, the military said.

The paratrooper's death brought to 203 the number of U.S. forces killed in and around Afghanistan since the Taliban was ousted in 2001.

The deadliest fighting was in southern Uruzgan province on Thursday, a separate U.S. military statement said. It started after a joint U.S.-Afghan patrol was attacked by militants firing assault rifles, mortars and rocket-propelled grenades. A U.S. service member and an Afghan soldier were wounded in this assault.

Shortly afterward, militants launched a second attack a few miles from the first, killing an Afghan soldier and wounding three others. No U.S. or Afghan casualties were reported in a third battle.

"A total of 13 enemy fighters were killed in the three engagements," the statement said. "Coalition aircraft and attack helicopters provided close air support for the operations."

In eastern Paktika on Friday, American troops attacked a group of militants as they laid a roadside bomb, capturing two and killing one as he tried to flee, a third U.S. statement said. A fourth rebel managed to escape.

Two mirrors used for signaling to other insurgents and blasting caps were found on the slain militant.

Elsewhere, suspected Taliban rebels fired at a vehicle late Friday in southern Helmand province, killing two brothers and a son of one of the victims, said Ghulam Muhiddin, a local, government leader.

The motive for the attack was not clear. One of the men was a candidate in legislative elections last month but had lost, Muhiddin said.

Militants also attacked Muslim worshippers on Friday, dragging two men from their prayers in a mosque in eastern Paktia province before killing both outside, and shooting to death a tribal elder as he prayed in neighboring Khost province, officials said.

Taliban-led rebels have stepped up attacks this year, leaving almost 1,500 dead. The violence is the deadliest since U.S.-led forces ousted the insurgents from power in late 2001 and has raised fears for the country's fragile democracy.