A homicide bomber in a police uniform detonated his explosives inside a police training center in southern Afghanistan on Monday, killing 21 officers and wounding at least 20, officials said. The Taliban claimed responsibility.

The bomber entered the training facility in Tirin Kot, the capital of Uruzgan province, as the police reservists were exercising, said Juma Gul Himat, Uruzgan's provincial police chief. The Interior Ministry said the attacker was disguised in a police uniform, a tactic Taliban militants have used in several high-profile attacks.

The Taliban has made a comeback the last three years after their initial defeat following the U.S. invasion in 2001. Southern Afghanistan is the center of their fight against the government and international military forces, and militants control wide swaths of territory.

The blast, which also damaged the compound, killed 21 policemen and wounded at least 20 others, Himat said. Nine of the wounded were sent to hospitals, while the rest were released after treatment, Himat said.

A Taliban spokesman, Qari Yousuf Ahmadi, claimed responsibility for the blast in a phone call from an undisclosed location. Ahmadi said the militants will continue to launch bomb attacks on Afghan government officials and foreign troops in the country.

Over the last several years, police have borne the brunt of militant attacks. In 2008, some 868 policemen were killed in insurgent attacks, according to a tally of figures collected by The Associated Press. More than 900 police were killed in 2007.