The rocket was undergoing a static fire test of the stage, in which a vehicle is clamped to a test stand while its engines are ignited, when the booster broke free. According to a statement from the company, the rocket was not sufficiently clamped down and blasted off from the test stand “due to a structural failure.”
Video of the accidental ascent showed the rocket rising several hundred meters into the sky before it crashed explosively into a mountain 1.5 km away from the test site.
Uh, I guess that’s why many of the more reasonable static test rigs have the rocket flat on the ground with a hill on the pointy side just in case.
That’s a different type of test for a different type of rocket.
That’s for testing engines alone. Static fire is separate yes way further down the line when you have the rocket built and ready to fly