KABUL, Afghanistan -- A multipronged militant assault on a small, remote U.S. base killed nine American soldiers and wounded 15 Sunday in the deadliest attack on U.S. forces in Afghanistan in three years, officials said.

The attack on the U.S. outpost came the same day a suicide bomber targeting a police patrol killed 24 people, while U.S. coalition and Afghan soldiers killed 40 militants elsewhere in the south.

The militant assault on the American troops began around 4:30 a.m. in a dangerous region close to the Pakistan border and lasted throughout the day.

Militants fired machine guns, rocket-propelled grenades and mortars from homes and a mosque in the village of Wanat in the mountainous northeastern province of Kunar, NATO's International Security Assistance Force said in a statement.

Nine U.S. troops were killed in the attack, a Western official said on condition of anonymity because he was not authorized to release the troops' nationalities.

NATO confirmed nine of its soldiers had been killed and 15 wounded. Four Afghan soldiers also were wounded, NATO said.

"Although no final assessment has been made, it is believed insurgents suffered heavy casualties during several hours of fighting," NATO said in a statement.

Lt. Col. Rumi Nielson-Green, the top U.S. military spokeswoman in Afghanistan, said she could not comment because the fight was ongoing.

The attack appeared to be the deadliest for U.S. troops in Afghanistan since June 2005, when 16 American troops were killed -- also in Kunar province -- when their helicopter was shot down by a rocket-propelled grenade.

Those troops were on their way to rescue a four-man team of Navy SEALs caught in a militant ambush. Three SEALs were killed and the fourth was rescued days later by a farmer.

Sunday's attack came during a period of rising violence in Afghanistan. Monthly death tolls of U.S. and NATO troops in Afghanistan surpassed U.S. military deaths in Iraq in May and June.

On July 7, a suicide bomber attacked the Indian Embassy in Kabul, killing 58 people in the deadliest attack in the Afghan capital since 2001.

In two other incidents this month, an Afghan government commission found that U.S. aircraft killed 47 civilians during a bombing run in Nangarhar province, while a separate incident in Nuristan province is alleged by an Afghan officials to have killed 22 civilians.

The high casualty tolls have prompted the International Committee of the Red Cross this week to ask all sides to show restraint and avoid civilian casualties.

But violence continued around the country Sunday.

A suicide bomber on a motorcycle blew himself up next to a police patrol Sunday in the southern province of Uruzgan, killing 24 people.

The bomb attack on a police patrol at a busy intersection of the Deh Rawood district killed five police officers and 19 civilians, wounding more than 30 others, said Juma Gul Himat, Uruzgan's police chief. Most of those killed and wounded were shopkeepers and young boys selling goods in the street, he said.

Elsewhere, Taliban militants executed two women in central Afghanistan late Saturday after accusing them of working as prostitutes on a U.S. base.

The women, dressed in blue burqas, were shot and killed just outside Ghazni city in central Afghanistan, said Sayed Ismal, a spokesman for Ghazni's governor. He called the two "innocent local people."