Surmad, Afghanistan ? U.S. jets carpet-bombed the mountains of eastern Afghanistan on Monday as coalition forces on the ground tried to block al-Qaida and Taliban escape routes. At least seven Americans were killed when two helicopters took enemy fire.

Fighting remained intense after enemy fire took down American aircraft for the first time since the war began Oct. 7. With the helicopters taking fire, the death toll of the new offensive reached nine Americans and several Afghans, Defense Secretary Donald H. Rumsfeld told a news conference at the Pentagon on Monday.

In one incident, a Chinook helicopter was shot at and crashed early Monday. Six died in the crash or an ensuing firefight on the ground, said a senior defense official of condition of anonymity.

In the second incident, the official said, one American was killed when a helicopter was fired on, made a hard landing and then managed to take off again.

An unknown number of troops also were wounded in the incidents, which occurred in an operation that started Friday against suspected al-Qaida and Taliban believed regrouping near Gardez in eastern Afghanistan.

Rumsfeld said “enemy forces have sustained much larger number of killed and wounded.”

Pentagon spokeswoman Victoria Clarke said she didn’t know whether a search-and-rescue operation was still under way for the Chinook that crashed.

The helicopter, normally used to ferry special forces troops and supplies, was downed on its way to the battle near Gardez.

Word of the shoot-down came after U.S. officials late Sunday reported intense firefights with several hundred fighters on the ground around the mountains of Paktia province, where the well-armed al-Qaida and Taliban fighters are believed holed up.

Coalition ground operations were accompanied by a fierce bombardment over the Shah-e-Kot and Kharwar mountain ranges surrounding Surmad that continued Monday as U.S. bombers tried to soften al-Qaida and Taliban positions in the snowcapped hills.

“In one minute, I counted 15 bombs,” Rehmahe Shah, a security guard at the intelligence unit in the provincial capital Gardez, said Monday.

U.S. Chinook helicopters had ferried in supplies to American and other troops in the hills following the start Saturday of the coalition ground attack in the area. In addition to at least 1,000 allied Afghan fighters and at least 1,000 U.S. troops, forces from Australia, Canada, Denmark, France, Germany and Norway were participating.

The assault was believed to be the largest joint U.S.-Afghan military operation of the 5-month-old terrorism war. Pro-U.S. Afghan troops approached the hide-outs from three directions to isolate the fighters and prevent them from escaping.

Safi Ullah, a member of the Gardez town council, or shura, said the first stage of the offensive was designed to cut the road from Shah-e-Kot to trap al-Qaida and Taliban forces in the mountains. He said the plan also involved setting up checkpoints in the area to prevent them from getting out.

Pakistan has closed its border with eastern Afghanistan and deployed extra army units and members of the Khasadar tribal militia to catch any who try to cross the frontier and filter into its Northwest Frontier Province.

Afghan officials say as many as 5,000 al-Qaida and Taliban fighters are regrouping in various parts of eastern Afghanistan and just over the border in Pakistan, urging the faithful to wage holy war against U.S. forces.

In the eastern Afghan town of Khost near the border, troops at the American-controlled air base called in air support early Monday after the base came under small arms fire, said Maj. Brad Lowell, another spokesman at the U.S. Central Command.

No one was injured and the firing stopped, he said.

An Afghan commander with troops at one of the fronts, Abdul Matin Hassan Kheil, said his men came under fire Sunday from mortars, heavy artillery and rockets fired from al-Qaida positions in the Shah-e-Kot range where Arabs, Chechens and Pakistanis were believed holed up.

“You can see it is a big operation,” said Kheil, who led 50 fighters. He said coalition forces were dug in about one mile from al-Qaida bases in the Shah-e-Kot mountains.

At least three Chinook helicopters, which zoomed toward the mountains Sunday afternoon flanked by two jets, were supplying ammunition and food to American forces still in the hills, he said.

Kheil estimated it would take a month to push the fighters from their mountain strongholds.

“These folks fight to the death, and it’s no different here,” Maj. Ralph Mills, a spokesman for the U.S. Central Command, said of the al-Qaida and Taliban fighters.

Sunday’s airstrikes repeatedly pounded targets in the Shah-e-Kot mountains, 20 miles east of Surmad and the Kharwar range to the west in Logar province.

Mills said that as of Sunday night, U.S. jets had dropped more than 270 bombs since the start of the offensive. He said targets included troop concentrations, vehicles, mortar positions, caves and anti-aircraft sites.

The bombardments sent thick, black plumes of smoke above the snowcapped peaks and shook the ground in Surmad, where a constant stream of bombers streaked overhead.

Mills said some Army Apache attack helicopters had sustained damage from ground fire.

Saturday’s ground attack, carried out in snow-covered mountains ranging from 8,300 to 11,600 feet above sea level, appeared to have made little headway in the dislodging Taliban and al-Qaida fighters.

The Afghan allies made up the bulk of the force and approached the front from three different directions, some of them using pickup trucks rented for $200 from the Gardez bazaar, Afghans said.

About 600 fighters accompanied by at least 40 U.S. soldiers approached from Gardez, north of Surmad, said Safi Ullah of Gardez. Another 400 Afghans came in from Khost to the east, and an undisclosed number came from Paktika province to the south.

After the ground attack stalled, U.S. planes late Saturday dropped a newly developed bomb designed to send suffocating blasts through cave complexes, military officials said. The “thermobaric” bombs were tested in December and officials said in January that they would be rushed to the region for the war.

Neither the former Taliban supreme leader Mullah Mohammed Omar nor al-Qaida chief Osama bin Laden is believed to be in the area.

But nearly two months ago, about 250 Taliban and al-Qaida soldiers told residents of Shah-e-Kot village, as well as 20 to 25 other villages tucked inside the mountains and foothills, to leave the area, said Haji Mohammed Gul, a resident of Murgurah-e-Khiel, near Surmad.

Initially, the villagers asked them to go away, he said. “But the Taliban and al-Qaida, with their Kalashnikovs, told them to leave.”