A suicide bomber walked into a crowd of mostly young spectators at a volleyball game in eastern Afghanistan and detonated his explosives vest on Sunday, killing at least 49 people, a provincial official said.

At least 60 more were injured in the attack in Sharana, capital of the Paktia province, where hundreds had gathered to watch the final match of an inter-district volleyball tournament, the official said. The explosion happened at the end of the game when the crowd was leaving, officials said.

A senior official with the ministry of the interior told NBC News that it appeared that the suicide bomb was designed to kill as many people as possible as it contained lots of ball-bearings — and that the casualties could go higher as most of the injured were in serious condition.

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Officials said most of the dead were youths but there were also 15 government employees killed, including two Afghan Local Police. No group has claimed responsibility for the attack, but local government officials were already pointing fingers at the Taliban.

Attacks across the country have escalated this year amid a contentious election and President Ashraf Ghani's inauguration in September. The insurgents use their attacks to make clear their opposition to Ghani's administration, as well as his support for a security agreement with the U.S., which he signed immediately after taking office.

Afghanistan's Parliament approved the agreement on Sunday with the U.S. and another with NATO allowing 12,000 international troops to remain in the country past the end of this year. U.S. President Barack Obama has approved an expanded combat mission authorizing American troops to engage Taliban fighters, not just al-Qaida terrorists. Obama's decision also means the U.S. can provide air support when needed.

The decision to expand the military's authority does not affect the overall number of U.S. troops who will remain in Afghanistan. Earlier this year, Obama ordered the American force be reduced to 9,800 by the end of this year, a figure expected to be cut in half by the end of 2015.

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— Fazul Rahim, with The Associated Press