Authorities in Afghanistan say suicide bombers have attacked official buildings in the volatile southern province of Uruzgan.

News reports say at least three bombers detonated their explosives Thursday and that other attackers were fighting police.

Officials said there were casualties from the blasts, but it is not yet clear how many. The attackers were reportedly targeting a government compound in the provincial capital, as well as the police chief's office.

On Wednesday, a suicide bomber killed the mayor of Afghanistan's southern city of Kandahar, the latest in a series of high-profile assassinations of key allies of President Hamid Karzai.

Witnesses say Mayor Ghulam Haider Hamidi was meeting with constituents about a land dispute when the bomber blew himself up near his office.

The Taliban claimed responsibility for the attack, which killed at least one other person. The group said the attack was to avenge the deaths of two children and a woman allegedly killed during the city's recent demolition of illegally constructed homes.

The mayor's death follows last week's targeted killing in Kabul of a member of parliament who also was a senior advisor to President Karzai. And earlier this month in Kandahar, a trusted bodyguard shot and killed President Karzai's half-brother, Ahmad Wali Karzai.

The increased violence comes as Afghans begin taking security control of parts of the country from U.S. and NATO-led forces.

About 33,000 American forces are set to leave Afghanistan by September of 2012. Last week, the first seven areas of Afghanistan were transitioned from NATO control to Afghan forces. Foreign combat troops are set to leave Afghanistan by the end of 2014.