Two children were killed when a suicide attacker believed to have been a woman blew herself up in a crowded area of western Herat city on Saturday morning, a senior police official said.
Another young girl, a woman and an elderly man were wounded in the attack, said Ikramuddin Yarwar, police commander in western Afghanistan.
He said pieces of blue cloth that looked like they had been part of a burqa, the all-covering article of clothing worn by many Afghan women, had been scattered around the site of the blast.
"Some pieces of burqa were seen at the site, so we are investigating if the attack was committed by a woman," he said.
"In this suicide attack one boy aged 10 and a girl aged seven were killed and a women, a girl of seven, and an old man were wounded," he said.
In other violence, the interior ministry said gunmen opened fire in a mosque in Jawzjan province on Friday, killing five men and wounding another two.
Six men had been arrested in relation to the incident, the ministry said in a statement.
A Danish soldier was killed today in southern Afghanistan and another was lightly wounded when their foot patrol came under fire in restive Helmand province, the Danish army said.