Businesses and TV personalities have offered US$315,000 to catch those responsible for a van blast in the US city of Nashville.
BBC News reports the explosion rocked the city early on Christmas Day, injuring three people and knocking out communications systems across the state of Tennessee.
Police believe the powerful blast was caused deliberately.
CBS News reports a person of interest, connected to the vehicle that exploded, has been identified.
No motive has yet been established for the explosion, and no-one has yet said they were behind it.
US media report possible human remains were later found near the blast site.
