Three different models of aircraft crashed in recent days in the U.S., killing 21 people in Missouri, California, and Texas, and leading to federal investigations into the causes.

A B-52 that crashed during a test flight at Edwards Air Force Base in California was in the air a very short time before slamming into the ground about halfway down the runway.

The U.S. Air Force says eight people aboard a B-52 bomber that crashed shortly after takeoff at a military base in Southern California’s Mojave Desert are dead.