You might recall that almost immediately it was reported that he was struck in the head with a fire extinguisher. That reporting remained the same for a number of weeks. More recently, it has been confirmed that the initial report was not correct and that he died from causes yet to be released — but not from being hit with a fire extinguisher.
When doing Emergency Operations Center (EOC) training, I have always stressed that when initial reports come into the EOC there has to be a bit of a filter for what is being reported. Who is the sender? Are they reporting something someone else has observed or are they on the scene? Is the person reporting the incident a trained first responder (looking at the credibility of the person)?
I use the example of how someone rolls up on a scene, and there is a car that is badly damaged in an explosion, and they report there has been a car bomb exploded. That could be the case, but perhaps there might just be a gas main that exploded right under the car. Combine a recent threat report of possible terrorist incidents happening and you can see how easy it is for someone to jump to conclusions.
One should not discount the first report that comes in, since there is an incident, but the details might not be what they first seem to be. Multiple reports coming from multiple sources reporting the same incident are helpful in determining the authenticity of the information being reported.
Note: I'm not saying don't react to the first report, but don't be part of the rumor mill that could quickly get started.
How did the report of Officer Sicknick being struck by a fire extinguisher get started? Likely the biggest culprit in the chain of events is the repetition of this information.