Authorities say some type of improvised explosive device was placed outside an Atchison barber shop and detonated.
It damaged eight businesses downtown. Investigators responding to an alarm found structural damage and broken windows throughout the downtown business block.
Fire Chief Ted Graf said no one was injured the incident early Friday.
The Bureau of Alcohol, Tobacco, Firearms and Explosives and Atchison police announced late Friday a $5,000 reward for information leading to an arrest of those responsible.
The device was placed outside Hair Spital Barber Shop, at 120 N. 8th St.
Surveillance footage captured a vehicle in the area moments before the device detonated. Police believe it is a 2004-2008 Nissan Quest.
Graf said the scene eventually was determined to be safe enough to allow business owners into their damaged stores. He said some stores might reopen Friday afternoon.
An investigation involving federal, state and local offices is continuing.
Anyone with information about the vehicle or the explosion is asked to contact the ATF at 888-283-2662 or through its website at www.atf.gov/contact/atftips. Tipsters can remain anonymous.
The Associated Press contributed to this story.