( CNN ) -- A suicide attack in eastern Afghanistan killed 25 people Tuesday , the police chief in Nangarhar province said . Chief Abdullah Stanikzai said the attack happened during the funeral of a local elder in the Dor Baba district , near the border with Pakistan . Fifty people were injured in the incident , local officials reported . Among the wounded was the district chief of Dor Baba , Stanikzai said . Afghan President Hamid Karzai condemned the attack , in a statement from his office . While it is not yet clear who was behind the blast , it is the latest of many to strike Afghan civilians . A recent United Nations report found that while violence against the Afghan population fell in the first half of the year , it is still taking a `` devastating toll on civilians . '' About 80 % of the attacks against civilians are by anti-government forces such as the Taliban , the report said . Nangarhar , which has Jalalabad as its capital and borders Pakistan 's restive Khyber Pakhtunkhwa province , has seen several recent International Security Assistance Force operations targeting militants . Afghan and coalition security forces arrested an alleged Taliban bomb-making expert in Nangarhar 's Khugyani district earlier Tuesday , an ISAF statement said . The man `` is believed to be a leading figure in the movement and provision of explosives for attacks against coalition and Afghan security forces throughout eastern Nangarhar , '' the statement said . Several other suspected insurgents were seized in the same operation , as well as firearms , military uniforms and explosives , it said . A separate operation last week in Nangarhar 's Hisarak district led to the arrest of an alleged Taliban insurgent accused of using his status as a member of the Afghan National Police to conduct an attack in May which killed two coalition service members in Helmand province , ISAF said . Prior to his capture , the man was attempting to join the Afghan National Army , ISAF said . U.S. forces take a leading role in ISAF operations in Nangarhar . CNN 's Masoud Popalzai contributed to this report .
NEW : 50 people were killed in the suicide attack , local officials say . At least 25 were killed in the attack , the police spokesman says . The district chief of Sai Baba was among those killed . No claim of casualties yet , but many such casualties come from the Taliban , a spokesman says .