Anti-Taliban forces launch ground offensive.(Knight Ridder Newspapers)

KABUL, Afghanistan _ Fortified with "doomsday" bombing by U.S. warplanes, anti-Taliban forces launched a ground offensive Saturday against the final Taliban bastion of Kandahar and met only modest resistance, opposition spokesmen said.

At the same time, a long column of U.S. military vehicles _ including light armor _ rolled into the desert from the U.S. Marines' base camp south of Kandahar, destination unknown.

The maneuvers intensified pressure on the key southern city that represents the last stand of the Taliban and its leader, Mullah Mohammad Omar.

By the end of the day, thousands of panicky residents fled Kandahar as anti-Taliban Afghans advanced from the north and east, and Marines patrolled to the south. U.S. bombs exploded relentlessly.

"We're pushing forward," Khalid Pashtun, an aide to anti-Taliban warlord Gul Agha Shirzai said via satellite telephone. "We're four kilometers (2.5 miles) short of the airport. There is heavy fighting going on."

His claim could not be independently confirmed, but Kandahar residents arriving at the Pakistani border reported fierce U.S. bombardments around the city and the airport, seven miles to the east.

"We saw the planes ...