KABUL, Afghanistan — Insurgents launched a brazen pre-dawn assault today against the giant U.S.-run Bagram Air Field, the second Taliban strike at NATO forces in and around the capital in as many days.

At least 10 insurgents were killed and seven U.S. service members wounded in the attack on Bagram, which started at about 3 a.m. with rockets, small arms and grenades fired into the base, said Maj. Virginia McCabe, a spokeswoman for U.S. forces at Bagram.

The gunfire finally subsided around midday, said another spokesman, Master Sgt. Tom Clementson.

"It's been a little while since we've heard any gunfire, but we're still maintaining a heightened security posture," he said.

The attack came one day after a suicide bomber struck a U.S. convoy in the capital of Kabul, killing 18 people. The dead included five American troops and a Canadian, making it the deadliest attack on NATO in the Afghan capital in eight months.

The back-to-back attacks appeared part of a Taliban offensive the insurgents announced earlier this month — even as the U.S. and its partners prepare for a major operation to restore order in the turbulent south. The insurgent attacks against both the capital and a major American military installation show the militants are prepared to strike at the heart of the U.S.-led mission.

The Taliban claimed responsibility for both the Kabul bombing and the attack at Bagram, 30 miles north of Kabul. Taliban spokesman Zabiullah Mujahid said 20 suicide attackers were involved.

A building was damaged in the attack, but it was "not a mission-essential building," McCabe said. She said while they could still hear occasional small-arms fire around the base late in the morning, "it is becoming more and more sporadic."

NATO's senior civilian representative in Afghanistan said insurgents had been repelled from an attempt to breach the base's defenses.

"We know that a group of insurgents sought to penetrate the air base, and that's been dealt with," Mark Sedwill said.

An Afghan provincial police commander, Gen. Abdul Rahman Sayedkhail, said the attack began when U.S. guards spotted would-be attackers in a car just outside the Bagram base. The Americans opened fire, triggering a gunbattle in which at least one militant triggered his suicide vest. Running gunbattles broke out as U.S. troops hunted down the other attackers.