At least 30 people were among the wounded, including seven Western soldiers, officials said.
The bomber, who was on foot, blew himself up in a crowded area in the southern province of Uruzgan, said Gen. Qassim Khan, provincial police chief. Schoolchildren were among those wounded, Khan said.
Maj. John Thomas, a spokesman for NATO's International Security Assistance Force, said seven NATO troops apparently on a foot patrol were wounded in the blast.
Most soldiers in Uruzgan province are Dutch, though NATO couldn't immediately confirm the wounded soldiers' nationalities.
Earlier Monday, an Afghan soldier opened fire inside a military base, killing an American and four Afghans, while a U.S.-led coalition raid in the east killed a Taliban leader and two children, officials said.
At a military base in the western city of Herat, an Afghan soldier killed three Afghan troops and a civilian, and wounded 12 others, said Lt. Col. David Johnson, a U.S. spokesman. An American soldier — an adviser training the Afghan military who was the apparent target of the rampage — was shot and later died of his wounds, the U.S.-led coalition said.
Gen. Fazeluddin Sayar, an Afghan commander, said the gunman told authorities he had a dream telling him to start jihad, or holy war. "That is why I came to kill this American," Sayar quoted the gunman as saying.
During the coalition raid at a home in eastern Paktia province, suspected militants fired guns and rocket-propelled grenades at the U.S. and Afghan troops, forcing the soldiers to return fire. Two children were killed in the exchange, said Maj. Donald Korpi, a U.S. spokesman.
"When someone shoots at you with an RPG, you're going to return fire," Korpi said. "It's very sad and we hate to see any civilian killed, especially a child. ... We had no indication whatsoever there were kids in there."
The midlevel leader killed in the raid was identified as Commander Saleem, whom the U.S. accused of having attacked Afghan and foreign troops. A woman inside Saleem's house was also wounded in the crossfire and evacuated for treatment, the coalition said.
Civilian deaths in Afghanistan have been a recurring theme this year and have dented Afghan support of the foreign military mission.
President Hamid Karzai has repeatedly asked international forces to do all they can to avoid such deaths. U.S. and NATO commanders say they frequently withhold fire if they think their attack will cause civilian casualties, but they reserve the right to defend themselves.
Afghan authorities, meanwhile, showed off a captured 14-year-old boy from Pakistan whom officials said had intended to set off a suicide bomb against an Afghan governor.
Afghanistan's intelligence service showed off the 14-year-old Pakistani boy, identified as Rafiq Ullah, at a news conference also attended by the boy's father, Mati Ullah. The two shed tears and hugged in front of journalists.