Three officers were shot and killed, and two others were critically injured Wednesday afternoon while serving a warrant in Pennsylvania.

Northrop Grumman's Cygnus XL experienced main engine troubles that have hampered its resupply mission to the International Space Station, NASA said.

On the same day that Tyler Robinson was formally charged with killing Charlie Kirk at a Utah university, a suspect was taken into custody for allegedly making threats against the same college.

The National Weather Service has issued air quality alerts in Texas, Tennessee, Mississippi, Arkansas, Missouri, Illinois, Indiana, Ohio and Kentucky.

The men's vehicle was found at a trailhead with their packs and their camping gear still inside