According to Afghan officials, the explosives exploded in front of a hospital near the local airport on Saturday.
"The blast occurred at around 0930 (local time) in front of a private hospital along a road leading to the Kandahar International Airport, killing three civilians," General Abdul Hamid Hamid, commander of the Afghan army regional corps, said.
The Kandahar airport, which is home to the biggest US military base in southern Afghanistan, has come under frequent militant attacks.
On Friday, the Taliban attacked a US consulate in western Afghanistan with car bombs and guns, killing 11 people, including four members of Afghan security forces.
At least 17 civilians were also injured in the consulate attack that took place in the city of Herat.
After the assault, the US evacuated many of its consular personnel to the embassy in the Afghan capital, Kabul.
The United States and its allies entered the war in Afghanistan in October 2001 as part of Washington’s so-called war on terror. The offensive removed the Taliban from power, but after nearly 12 years, the foreign troops have not yet been able to establish security in the country.
RA/HH