the first girl supposedly shot inside the bus

At one point there was a great deal of hysteria among the other hostages concerning Sandro having shot one of the girls inside the bus long before he decided to walk out, causing a lot of screaming about the victim lying bleeding and dying on the floor, and as I recall this was before he told the other hostages to feign hysteria in general (though I may be mixing up the timeline). In any case the end of the film deals only with the shield hostage who was actually killed by the cop who shot at Sandro at point-blank range after they finally exited. So did Sandro in fact shoot anyone while inside the bus, or was that whole episode just a scripted ploy, with the other girls play-acting, and no one was actually shot on the bus? Even if one of the hostages had been shot but not killed -- or if that whole episode was simply a sham -- you would think the film would have addressed and cleared up this question -- assuming this wasn't just a case of my missing the explanation.

Help, anyone?

Also, I felt it was unfortunate that Padhila was forced to elide over what really happened to Sandro at the hands of the police once he had been hustled into the police car away from the lynch mob, but I suppose there was practically no video stock beyond his being tossed into the car, and almost no cooperation from the police or coroner in describing the details of his fate.

About the use of negative film stock in the interviews with prisoners in the jail, this was just a method of attempting to disguise the interviewees to protect their privacy, for much the same reason that all minors shown in the film have their faces blurred out.

Anyone interested in this movie might also want to watch Hector Babenco's 1981 Pixote, about street children, or his 2003 Carandiru, about prison conditions. City of God (2002), by Fernando Meirelles, may also be of interest for additional insight.