The FBI is helping investigate an explosion near the Colorado Springs chapter of the NAACP.

The blast happened Tuesday outside a barber shop next door to the group's building, which is about an hour south of Denver. Police say no injuries were reported.

FBI spokeswoman Amy Sanders it's not known yet whether the explosion was an accident or not or whether it was aimed at the nation's oldest civil rights organization.

The extent of the damage from the explosion wasn't immediately clear. Photos of the scene don't show any visible damage to the barber shop building.