KABUL, Afghanistan – Security forces arrested a deputy of a top Taliban commander yesterday for a bomb attack that wounded three American soldiers, and an American soldier died when an Air Force helicopter crashed on a nighttime mission to rescue an election worker.

President Karzai, meanwhile, nudged closer to victory in Afghanistan’s landmark presidential poll with nearly two-thirds of the vote counted – although his huge lead narrowed slightly as the third-and fourth place candidates gained some ground.

The October 9 election, hoped to usher in peace after two decades of war, was a setback to Taliban terrorists who failed to deliver on threats to derail the vote. Yet they continue to launch sporadic attacks in the lawless south and east of the country.

A homemade bomb destroyed two American Humvees in southeastern Paktika province near the Pakistan border, wounding three American soldiers, one critically, and their Afghan interpreter, an American military statement said.

Paktika Governor Gulab Mungal said Afghan forces later arrested a suspect in the attack, whom he identified only as a deputy of Jalaluddin Haqqani, a frontline Taliban commander who served briefly as tribal affairs minister before the fall of the terrorist Islamic regime in late 2001.He remains at large.

Mr. Mungal said several land mines, explosives, and bomb-making instructions written in Arabic were seized from the suspect’s house.

There was no immediate claim of responsibility for the attack on the Americans, but Abdul Hakim Latifi, who claims to speak for the Taliban, vowed yesterday the rebels would continue their “holy war” against the American led coalition forces and the Afghan government.

“If the government holds elections 100 times this will not change the Taliban’s commitment to jihad. The Taliban will pursue jihad until death,” he said by satellite phone from an undisclosed location.

Meanwhile, an American Air Force helicopter accidentally crashed late Wednesday in a remote western region near the border of Ghor and Farah provinces during a mission to rescue an injured Afghan election worker, officials said. The pilot was killed and two other airmen were injured, one critically.

U.N. spokesman Manoel de Almeida e Silva said the election worker had been shot accidentally by his Afghan armed escort. As it was dark, U.N. helicopters were unable to evacuate the casualty, who was bleeding heavily, so they sought American help – only for the better-equipped American military HH-60 helicopter to crash as it tried to land.

The three Americans and the injured election worker were taken by another U.S. helicopter for medical treatment in Kandahar, then transferred to the main American base at Bagram. One of the Americans – identified by the U.N. spokesman as the pilot – later died.

American military spokeswoman Lieutenant Colonel Pam Keeton said that technical problems – not hostile fire – brought the helicopter down, and that the accident was under investigation.