Authorities say at least four people were killed and seven were wounded, when a suicide bomber blew himself up in a soccer stadium in northwestern Pakistan.
Police official Faisal Mukhtar said Sunday's bombing apparently targeted refugees from the nearby Khyber tribal region as they registered with the government.
No one immediately claimed responsibility for the attack.
Thousands of people from the Khyber tribal district have fled their homes to avoid clashes between government troops and the local Taliban. Pakistan has been housing them in refugee camps.