LASHKAR GAH, Afghanistan - A suicide car bombing in front of a local police chief's office on Tuesday killed two civilians and wounded 26 in a southern Afghan city chosen to pioneer a transition to Afghan security control, hospital and government officials said.

The Taliban immediately claimed responsibility for the attack in Lashkar Gah, a city in which responsibility for security was handed over from foreign forces to their Afghan counterparts two months ago.

The car bomb exploded in a busy street close to shops and government offices. One of those killed was a child and 10 police were among the wounded, said Daoud Ahmadi, a spokesman for the governor of Helmand province.

He said the bomb exploded close to a bakery that supplied bread to local police.

The handover of Lashkar Gah in July, from NATO-led coalition troops, was seen as a critical test of the readiness of Afghan forces to assume control of security affairs.

It was one of the first six areas chosen to kick off a gradual withdrawal of foreign troops that will end with the return home of all NATO-led combat troops by the end of 2014, and the one that posed the biggest security challenge.

Qari Yousuf Ahmadi, a spokesman for the Taliban, claimed responsibility for the attack in a text message sent to reporters.

Helmand, bordering Pakistan, is an insurgent stronghold in which more foreign troops have been killed during the decade long war than any other province of Afghanistan.