Most newspapers subscribe to various news sources, the Associated Press, for instance. So when anything of any real interest beyond just very local news, each subscribing paper has the option to post the story on the wire for other newspapers to pick it up. These stories are frequently updated as more facts are known.
This is why all major newspapers carry big news stories with or without a byline that will specify (AP) nest to the dateline. So reporters for some of the major Washington D.C. papers, like The Washington Post, or Washington Times write their story for their own paper while serving it up to be used by any subscribing major newspaper around the country. The same is true for sports stories. Every major baseball or football team is covered locally by several area newspapers. The Browns for instance are covered by The Plain Dealer, The Akron Beacon Journal, The Warren Tribune-Chronicle and others. Any of their stories about Browns practices or games can show up in the Buffalo News the week that the Browns play Buffalo, because they pick up these stories posted on the AP wire.
Newpapers also can choose to subscribe to syndicates (where they get comics, DEar Abby, etc.) or to specific newspaper wires. So newspapers in Ohio might subscribe to the Columbus Dispatch to get major stories from the state's capital where the state offices are located, or The Plain Dealer.
Broadcast news, local like you local NBC affiliate in your city, and national like NBC Nightly News with Brian Williams, also subscribe to these wires, along with their affiliate station's reporters in major cities across the country. They often will tape or carry a live feed from their affiliate's coverage, but if it is a big story and one that has legs (is gonna be around awhile) they have their own producers and reporters who fly out to get their own coverage. Some of their reports are planned days or even weeks ahead, others at the spur of the moment. They also watch other stations' broadcasts to keep up with what all the other news stations are covering or breaking over the air. So, if CNN flashes a news alert of some disaster in Iowa, they contact their nearest affiliate or send a producer, cameraman and reporter to the site. Often, they will use the affiliate's equipment including the local satellite truck.
Hope this helps clear it up a bit.