A suicide bomb exploded in crowds at a traditional horse-back game of buzkashi in northern Afghanistan on Wednesday, killing at least eight people, police said.
Among the dead were the district police chief and the father and brother of the Speaker in the national parliament, the police chief of Kunduz province Abdul Khalil Andarabi said.
Several other people were wounded in the attack with some critically injured. "The suicide attacker detonated himself at the end of the match in Imam Sahib district this evening," Andarabi told AFP.
Buzkashi is Afghanistan's national sport in which riders use a headless goat in place of a ball in a ferocious version of polo.
Kunduz, which borders Tajikistan, has been beset by militant violence in recent years. In 2010, the provincial governor was killed by a bomb blast that tore through prayer services at a mosque.
"President Hamid Karzai strongly condemns the suicide attack and says that terrorists have once again killed and injured innocent people," a statement from the president's office said.
Afghan soldiers and police are taking over security across the country as international coalition troops, who have been deployed since 2001, pull out by the end of next year.
There was no immediate claim of responsibility for the attack, but the Taliban regularly launch suicide attacks and are active in Kunduz province.
The attack on Wednesday followed twin suicide explosions on Sunday, when a total of 19 people were killed in blasts in the capital Kabul and in the eastern province of Khost.
The bomb in Kabul, outside the defence ministry, struck as US Defense Secretary Chuck Hagel visited a US military base nearby in the city centre.
The latest violence came after President Hamid Karzai accused Washington of colluding with the Taliban insurgents to justify the US presence in the country.
The White House strongly rejected the allegations, saying the US has "spent enormous blood and treasure" in supporting the Afghan people since 2001 and did not support any kind of violence involving civilians.
The two countries have started an arduous transition phase in which the 100,000 NATO-led troops exit Afghanistan and local forces take on fighting the Taliban alone.
The United States and Afghanistan are also negotiating a strategic pact that will determine the US presence in Afghanistan after the end of the international combat mission.