agent,
Three things come to my mind.
Either that person was not a member, just someone with lights and sirens that took unreasonable and dangerous risk and broke the law.
Either the call has been canceled or downgraded, (for instance as the first person the scene radios to the other units responding that they can downgrade it and proceed without lights and sirens.
Or, this was a bad apple, someone that misused and abused his L&S.
There is no real way of knowing what really happened. I know that it looks upsetting when you see someone turning on his L&S only to shut it a few minutes later, however there might be a legitimate reason as to why he did so.