NEW YORK - The Colorado school shooting temporarily pushed pictures of panic and horror from Yugoslavia off TV screens Tuesday, replacing them with similar scenes from this country.

It was adrenaline television, most of it beamed to the nation from local news operations in Denver. There were gripping pictures of students running from the school, relieved reunions with parents and crying, anxious people wondering where their loved ones were.

As the day wore on, the news became grimmer.

ABC, CBS and NBC broke into regular programming to give details, but it was primarily a story for the cable news networks.

CNN's coverage was similar to MSNBC's early in the story, since both relied primarily on reports from KUSA-TV, the NBC affiliate. Fox News Channel used pictures from KMGH-TV, the ABC affiliate.

CNN's effort to secure affiliate agreements with 600 local stations in the United States and Canada paid off for the news network, since it was able to choose from among pictures provided by four separate local stations.

"That's a considerable amount of journalistic heft,'' said Earl Casey, CNN senior vice president. Its rivals relied primarily on their own affiliates as they rushed to get journalists to the scene.

By coincidence, CNN reporter Tony Clark was landing in Denver to cover a story on aircraft being used in the Yugoslavian conflict Tuesday afternoon, and he was quickly dispatched to the school shooting.

While the siege was continuing, MSNBC said it was careful not to televise aerial pictures that showed activities of police SWAT teams, on the chance that suspects inside the school may have had access to TV.

"We are constantly aware of security issues and not showing pictures that would jeopardize the safety of students,'' MSNBC spokesman Cory Shields said.

However, MSNBC did show pictures of students being evacuated from Columbine High School and cowering in a corner to try to stay out of sight of anyone inside the school building.

CBS quickly announced it was airing a "48 Hours'' special on the shooting Tuesday, calling it "Young Guns.''