Suicide bombers and armed men have stormed an Afghan police compound in Kandahar, setting off explosions and firing assault rifles in a co-ordinated attack, killing six members of the country's security forces.
Thursday's attack began when four suicide bombers stormed the police complex, Zulmi Ayubi, a spokesman for the provincial governor, told the Associated Press news agency.
Three of the bombers blew themselves up, Ayubi said, while the fourth man exchanged fire with Afghan troops.
However, a police official, speaking on the condition of anonymity, said several attackers were armed with assault rifles and rocket-propelled grenades.
Zalmai Ayoubi, a spokesman for the Kandahar governor's office, said three attackers were killed in the standoff. The complex is also used as an army and police recruitment centre.
US Black Hawk helicopters and at least eight US armoured vehicles rushed to support dozens of Afghan troops battling the assailants at the three-building police complex.
Major Randy Taylor, a spokesman for the US-led International Security Assistance Force (ISAF), told the AFP news agency that the attackers failed to gain access to the complex, despite trying to smuggle in a car bomb in a vehicle disguised as an ambulance.
"I heard a blast and after that continuous fighting with rocket launchers," Ashrafullah Agha, Kandahar provincial policeman, told AP.
After a third large explosion, Agha cut off the interview.
Khan Mohammad Mujahid, Kandahar's police chief, said that four intelligence officers were killed in the fighting, along with an Afghan soldier and a police officer. He said 12 police were wounded.
The Taliban claimed responsibility for the assault.
Yousuf Ahmadi, a Taliban spokesman, told the AFP news agency that four of their fighters had entered the police centre, saying it was "currently on fire and there is a lot of smoke from the compound".
The police complex sits near the main highway between Kandahar and the capital of Kabul, 148 miles to the north. A weapons training school and police literacy centre are located inside the complex.
Kandahar is a Taliban stronghold that has seen some of the most intense fighting of the 'war on terror'.
The attack is the latest to target Afghanistan's roughly 120,000-strong police, who will play a growing role in the country's security as international troops start a limited withdrawal from seven more peaceful areas in July.
Also on Thursday, NATO announced that it had concluded what it described as a "significant operation" in mountainous eastern Kunar province, near the border with Pakistan.
More than 80 fighters were killed after joint Afghan and international forces cleared four villages, NATO said.
"The combined security force moved into the mountainous area near the Pakistan border in order to disrupt insurgent activities in the region," NATO said in a statement.
"Insurgents had been using the area to move supplies and men into Kunar province and to stage attacks on Afghan and coalition forces."
Afghanistan's defence ministry said late on Wednesday that more than 130 fighters had been killed in the area over the past two weeks.
Few details havebeen released, but at least six US soldiers were killed in the area last week.