Hours later, a suicide car bomber rammed into a convoy that usually carries Kandahar Gov. Asadullah Khalid. The governor was not in the convoy, but the apparent assassination attempt killed three civilians on the street and wounded four government employees, including the information and culture minister and one of Khalid's body guards.
The blasts in Kandahar came less than a week after Taliban field commander Mullah Dadullah was killed during a U.S.-led operation in neighboring Helmand province.
The Taliban claimed responsibility for the first two attacks in their former stronghold, saying that the second blast was timed to hit as more police arrived on the scene.
The first blast - a remote-controlled bomb targeting a pickup truck - killed four private security guards, said Esmatullah Alizai, Kandahar province's police chief.
About 15 minutes later, a second remote-control bomb exploded, killing three policemen and wounding four, Alizai said.
Several journalists covering the aftermath of the primary explosion were splattered with blood from the deafening blast. Two journalists working for Al-Jazeera television were slightly wounded, taking shrapnel to the back of their legs.
President Hamid Karzai condemned the attackers as "enemies of Afghanistan," saying the militants were harming police and civilians.
"Through these attacks they are trying to disrupt the process of development and reconstruction of Afghanistan, but the people of Afghanistan are confident that the enemy will fail in their mission," he said in a statement.
The first bomb sent the pickup truck cascading off the road, and left it a charred, burning wreck. The second bomb ripped through the bystanders - mostly police and journalists, as civilians were barred from entering the area. The severed leg of one policeman landed near an Associated Press reporter. Another dead officer in bloodied, white clothes lay on the ground 10 yards away.
Officers shouted and cried as they carried bodies away in the chaos.
Kandahar has seen such double attacks before - a tactic often used by insurgents in Iraq - but they are still comparatively rare in Afghanistan.
Qari Yousef Ahmadi, a purported Taliban spokesman, said the attack was planned to target police responding to the first bomb.
"First we set off a remote control explosion on a police vehicle, then we were waiting for the police to arrive on the scene, then we did a second blast," Ahmadi said by satellite phone from an undisclosed location.
There was no immediate claim of responsibility for the bombing of the government convoy, but it was the kind of attack often blamed on the Taliban.
The Taliban have warned of "bad consequences" if the government didn't hand over Dadullah's body to his relatives. Khalid has said that Dadullah was buried at a secret location near Kandahar.
"After the Dadullah killing the Taliban have been trying to disturb law and order in Kandahar province," Khalid said after the attack on the convoy Thursday evening. "But they can't do it. We are working our hardest to secure the city and the province."
In Helmand on Thursday, insurgents ambushed a joint NATO and police patrol, firing a rocket at the NATO vehicle and engaging in a gunbattle, causing some casualties, officials said.
Sangin district police chief Ghulam Wali said the joint forces were patrolling on foot, and he believed only the driver was in the NATO vehicle when it was hit by the rocket. Fighting continued into the evening.
NATO's International Security Assistance Force confirmed there was an incident in Helmand with casualties, but did not immediately have any further details.
Wali said the attack was possibly related to a Taliban-linked drug trafficker who lived near the scene of the attack. About 1,600 people, have been killed in insurgency-related violence this year, according to an AP count based on U.S., NATO and Afghan officials. The dead have mostly been militants, but nearly 300 civilians have also died in the violence.