Afghanistan was hit by multiple militant attacks across the country Wednesday, as the U.S. military announced it carried out a successful airstrike targeting top Taliban leaders.

Officials said Wednesday a suicide bomber struck outside the Interior Ministry in the capital, allowing gunmen to pass through an outer gate where they traded fire with security forces, who eventually killed all the attackers.

Gen. Daud Amin, the Kabul police chief, says seven attackers were killed in Wednesday's shootout and that cleanup operations are underway. Interior Ministry spokesman Najib Danish says one policeman was killed and another five were wounded.

It appeared to be a rare victory for Afghan security forces, who have struggled to secure the capital in recent months.

Earlier in Loghar province, east of Kabul, the Taliban claimed an attack on a police station in the provincial capital Pul-e Alam which killed three police and wounded 12, among them four police and eight civilians.

Shahpoor Ahmadzai, a spokesman for the provincial governor, said three attackers who sought to enter the police station in the early morning hours triggered a three-hour gunbattle that ended when all three were killed.

Also on Wednesday a vehicle bomb in the southern city of Kandahar went off inside a garage where Afghan army vehicles were being repaired, killing three mechanics and wounding 13 people, governor's spokesman Daud Ahmadi said. No group immediately claimed responsibility.

Meanwhile, the U.S. military announced Wednesday that an artillery strike killed more than 50 senior Taliban commanders in Afghanistan's southern province of Helmand.

The attack on a meeting of commanders in the district of Musa Qala in Helmand, one of the heartlands of the Taliban insurgency, was a significant blow to the insurgents, said Lt. Col. Martin O'Donnell, spokesman for U.S. forces in Afghanistan.

O'Donnell said a weapon system known as the High Mobility Artillery Rocket System, or HIMARS, which is capable of firing GPS-guided rockets, destroyed the command-and-control position, a known meeting place for high-level Taliban leaders.

"It's certainly a notable strike," he said, adding that several other senior and lower level commanders had been killed during operations over a 10-day period this month.

The U.S. military said the May 24 meeting involved commanders from different Afghan provinces, including neighboring Farah, where Taliban fighters briefly threatened to overrun the provincial capital this month.

"We think the meeting was to plan next steps," O'Donnell said. While the strike by an artillery rocket system would disrupt Taliban operations, it would not necessarily mean any interruption to the fighting, he said.

The Taliban dismissed the report as "propaganda" and said the attack had hit two civilian houses in Musa Qala, killing five civilians and wounding three.

"This was a civilian residential area, which had no connection with the Taliban," spokesman Qari Yousaf Ahmadi said in a statement.

U.S. officials have sought to compel the Taliban to enter peace talks by increasing the military pressure on them.

Last week, a U.S. government watchdog group said the administration's revamped strategy has made little progress against the Taliban insurgency, leaving the country a "dangerous and volatile" place nearly 17 years after the U.S. invaded. That conclusion contrasts with assertions last fall by the American military that the Afghans, with U.S. support, had "turned the corner" and captured momentum against the Taliban, which it called fractured and desperate.

The report to Congress by inspectors general of the Pentagon, the State Department and the U.S. Agency for International Development also cast doubt on the administration's decision to send a new set of military advisers this year to work with Afghan forces closer to the front lines. It said this, combined with stepped-up Afghan offensives, "further raises the risk of civilian casualties, insider attacks, U.S. casualties, and other conflict-related violence."

The U.S. has about 15,000 support troops in Afghanistan, mostly providing various forms of military assistance.