A suicide bomber in Afghanistan's southern Helmand province detonated his explosives-laden car Sunday, killing 12 police officers and a child and wounding a dozen others.
A spokesman for the provincial government (Daoud Ahmadi) in the capital, Lashkar Gah, said the blast occurred outside the heavily guarded police headquarters. It is the first major attack in the area since Afghan forces took over full security responsibility from NATO-led troops less than two weeks ago.
Taliban militants have claimed responsibility for the attack.
Sunday's assault is the latest in a string of regional attacks that have included the assassination of several high-profile officials, including Mr. Karzai's half-brother and the mayor of Kandahar city in neighboring Kandahar province.
In other violence Sunday, NATO said five of its service members died in three separate incidents. A NATO statement said three troops died as a result of a non-battle related injury in western Afghanistan, another one was killed in a bomb blast in the east and the fifth died in an insurgent attack in the south.
The blast in Helmand came as the top U.S. military officer met with commanders and troops in southern Afghanistan on the second day of an unannounced visit.
Admiral Mike Mullen said the new U.S. commander in Afghanistan, Marine Corps General John Allen, is working on plans for the initial withdrawal of 10,000 American troops from the country by the end of the year. He said General Allen has until mid-October to submit his plan.
Military officials say the pullout may hinge on whether the latest surge in attacks continues through the holy month of Ramadan, which starts Monday. Mullen says Taliban leaders are reportedly pushing for an increase in violence during Ramadan and may leave their fighters in the country while top commanders spend at least part of the holy month in neighboring Pakistan.