Wikipedia has casualties between 129,000–246,000:

http://en.wikipedia.org/wiki/Atomic_bombings_of_Hiroshima_an...

Casualties and losses: 20 U.S., Dutch, British prisoners of war killed 90,000–166,000 killed in Hiroshima 39,000–80,000 killed in Nagasaki Total: 129,000–246,000+ killed

It doesn't say if these are all immediate casualties (does it even matter), but it does mention estimates for Nagasaki immediate casualties is between 22,000-75,000.