GANJGAL, Afghanistan — We walked into a trap, a killing zone of relentless gunfire and rocket barrages from Afghan insurgents hidden in the mountainsides and in a fortress-like village where women and children were replenishing their ammunition.

"We will do to you what we did to the Russians," the insurgent's leader boasted over the radio, referring to the failure of Soviet troops to capture Ganjgal during the 1979-89 Soviet occupation.

Dashing from boulder to boulder, diving into trenches and ducking behind stone walls as the insurgents maneuvered to outflank us, we waited more than an hour for U.S. helicopters to arrive, despite earlier assurances that air cover would be five minutes away.

U.S. commanders, citing new rules to avoid civilian casualties, rejected repeated calls to unleash artillery rounds at attackers dug into the slopes and tree lines — despite being told repeatedly that they weren't near the village.

"We are pinned down. We are running low on ammo. We have no air. We've lost today," Marine Maj. Kevin Williams, 37, said through his translator to his Afghan counterpart, responding to the latter's repeated demands for helicopters.

Four U.S. Marines were killed Tuesday, the most U.S. service members assigned as trainers to the Afghan National Army to be lost in a single incident since the 2001 U.S.-led invasion. Eight Afghan troops and police and the Marine commander's Afghan interpreter also died in the ambush and the subsequent battle that raged from dawn until 2 p.m. around this