The statement is perfectly correct, it states whether they witnessed anything...not whether they heard anything, police would need clear identifications of the suspects to actually do anything, everyone knows what the crack of a bullet sounds like.

Sounds like the bus was very busy, probably over crowded...not sure about other people but when im on a bus i generally look out the window, listen to my walkman or play on my phone..unless of course i am with someone in which case i talk to them.

Although there were 40 people on the bus i bet a very small percentage of them actually saw the actual incident take place and have enough proof it was he/she to stand up and say it in court, either that or they are scared for their lives....also don't forget it does say the shooting started at the back of the bus in which case no one would have witnessed the initial exchange.