A homicide bomber ran onto a police training field and blew himself up, killing up to 10 policemen and wounding dozens of others Monday in northern Afghanistan, officials said. The Taliban claimed responsibility for the deadly strike.

The homicide attack happened in the relatively quiet city of Kunduz, as police were carrying out their regular morning exercises, said Abdul Hadi, a security official. Hadi said that according to preliminary reports, 10 police were killed and 10 were wounded.

Azizullah Safar, chief of the Kunduz hospital, said nine of the victims brought to his hospital had died and 32 were wounded, including four in critical condition.

• More coverage of the struggle for stability is available in FOXNews.com's Afghanistan Center.

A purported Taliban spokesman, Qari Yousef Ahmadi, told The Associated Press by telephone that the Taliban carried out the attack, but his claim could not be independently verified.

The north is one of the quietest places in war-torn Afghanistan, and militant violence there is rare.

In Ghazni province, southwest of Kabul, a clash Sunday between Afghan forces and insurgents left 15 militants dead and 15 wounded, Interior Ministry spokesman Zemeri Bashary told reporters Monday.

Also Sunday, a homicide bomber targeted a private U.S. security firm in violence-wracked southern Kandahar province, killing up to four Afghans working for the company and wounding another, officials said.

The security firm U.S. Protection and Investigations said a homicide bomber riding a motorcycle blew himself up near a convoy, killing two employees and wounding another.

Mohammad Asif Khan, a police officer in Kandahar's Spin Boldak district, said three security guards and their driver were killed, Khan said. The differing death tolls could not immediately be reconciled.

Separately in the eastern Paktika province, police and U.S.-led coalition forces attacked suspected Taliban insurgents crossing from Pakistan into Afghanistan, killing 10 militants and wounding 15, the provincial governor said Sunday.

Afghan and western officials have stepped up pressure on Pakistan to crack down on militants who organize and train in Pakistan's tribal areas, and then cross the border to launch attacks and wreak havoc in Afghanistan.

The latest violence comes as more than 5,000 NATO and Afghan troops are engaged in Operation Achilles, launched last month to flush out militants entrenched in opium-producing Helmand province.

Visit FOXNews.com's Afghanistan Center for complete coverage.