Eight schoolchildren are amongst at least 13 people killed in a bomb blast in the Afghan city of Kandahar.
Bloodied clothing and debris littered the scene of the bombing
Nearly 60 others were injured in the explosion, security officials say.
The bomb went off just as passers-by had gathered around the scene of a smaller explosion nearby which had taken place minutes before.
The blasts occurred near an Afghan army base - similar attacks have in the past been blamed on Islamist guerrillas resisting US troops in Afghanistan.
Witnesses say the area around the blast was covered in broken glass and bloodstains.
One man was arrested near the scene of the explosion.
Afghanistan's President, Hamid Karzai, condemned the attacks, saying those who had carried them out were enemies of peace and prosperity.
Kandahar is the spiritual home of the ousted Taleban militia which governed Afghanistan until a US-led invasion in 2001.
Foreign workers and soldiers have been on their guard in Kandahar
Supporters and remnants of the Taleban have been blamed for rising violence and instability in the region.
Spokesmen for the Taleban movement have declared a holy war against foreign aid workers and soldiers in Afghanistan.
On Monday, there was a gun-and-grenade attack at a cabin housing security guards outside the offices of the UN's refugee agency in Kandahar.
No one was hurt in the attack.
In November 2003, a car bomb explosion outside UN offices in Kandahar injured one Afghan.
In December, 16 people were injured by a bomb left on a bicycle in a crowded Kandahar bazaar.
Tuesday's explosions came minutes before the governor of Kandahar's province, Yusuf Pashtun, was to pass through the area, the AFP agency reports.
On Sunday, delegates at a tribal gathering in Kabul endorsed a new constitution for Afghanistan, after weeks of wrangling between different ethnic groups and power-brokers.