One of the posts here said the bus driver was taken to the hospital. That would be at least injured, and there was the student reported to have the red face from being so close to the blast. Interesting the article was changed after being released.
I saw the later article that said the bus driver was taken to the hospital, but wondered about its accuracy. The SoonerFan who talked to one of the bus drivers said that the knocked-down bus driver was spending the night with the FBI and local constabulary (police/constables). He said he was unhurt.
If he was sent to a hospital (or otherwise in some type of protective custody until his witness account could be documented), maybe there are others, too, that we con't know about.