( CNN ) The FBI is investigating an explosion outside a local NAACP chapter in Colorado . A makeshift bomb , or improvised explosive device , detonated Tuesday morning but failed to ignite a gasoline can placed alongside it . No one was injured , but the incident left some shaken in Colorado Springs . `` All of a sudden I heard this big boom , '' one witness told CNN affiliate KDVR-TV in Denver . `` There was smoke everywhere ; the building on the side was burnt . '' The witness continued : `` Whoever did it took off right away though . That 's all I heard and it was scary . '' The FBI 's Denver office said it 's looking for a balding man , about 40 , who was seen leaving the scene in a white pickup with a missing or covered license plate . Another witness , Julie Skufca , told KDVR that she stared at a man as he drove away calmly . `` ( It ) kind of made your heart stop , especially when you have kids , '' she told the station . `` He was a heavier white man with what looked like a ( Carhartt jacket ) '' she added . `` Just driving normal like it was a normal day . '' The FBI has not said if the NAACP was targeted . But some pointed out that the other building tenant , Mr. G 's Hair Design Studios , likely was not . `` Who would want to bomb a beauty salon ? '' one member of the local NAACP chapter told CNN affiliate KCNC-TV in Denver . Henry D. Allen Jr. , the branch 's president , also raised the specter of a targeted attack , telling KCNC , `` Apparently , we 're doing something correct . Apparently , we have gotten someone 's attention that we are working toward civil rights for all . That is making some people uncomfortable . '' The NAACP is the nation 's oldest civil rights organization . The group 's national office says it is looking forward to a `` thorough investigation '' into the explosion by national and local authorities . The FBI has asked that anyone with information call its Denver tip line at 303-435-7787 . CNN 's Michael Martinez contributed to this report .
Witness says man fled `` just driving normal like it was a normal day '' No one was injured , but blast leaves some shaken in Colorado Springs . NAACP branch president : `` Apparently we have gotten someone 's attention ''