I'm seeing this more and more constantly and I have a feeling this is done on purpose. News outlets always want to be the "first" to get their hands on a breaking story because to them, that equals more ratings. But more ratings doesn't always equal quality service. Same thing with weather reports; often times big market stations will hype up a major storm and when it arrives it could be nothing more than a slight inconvenience.
Media outlets tend to put the carriage in front of the horse, in an attempt be the groundbreaking source of information. This expediency comes at the price of credibility. Media consumers expect accurate and timely information, and the media has a responsibility to provide it by vetting the information distributed. It's irresponsible to chase ratings by trying to be fastest. To be the most accurate would be a better goal for the press to focus on.
Many times, the news media has guessed or alluded to details or facts that later turn out to be false. In the early reporting of the Navy Yard shooting and the Sandy Hook, they reported several gunmen, and it turned out to be one. The media is consumed with sensationalism and trying to be the first to report the facts. They want to "wow" their audience into thinking they are getting the juicy details in order to inflate their ratings. They are no longer prioritizing their ethical responsibility to report objectively.
I feel that news does backtrack quite a bit in today's information based world. This is a product of two occurrences. First, the speed at which information can be communicated is much faster than it was 50 years ago. This leads to inconsistencies in reporting as seen during 9/11 and the Sandy Hook shooting for examples. Second, news outlets strive to be the first to bring information to the public. This is commonly done at the sacrifice of accuracy.
It's very hard for news outlets to strike a balance of reporting news that happens to the minute, but at the same time, making sure that the news is accurate. Sometimes, there are going to be mistakes. I would rather the news tell me what they think they know, and I can be the judge of its accuracy.