BROWNSVILLE, Texas (NewsNation Now) —  The SpaceX high-altitude flight test of Starship SN11 prototype Tuesday ended in an apparent crash and explosion on impact.

The prototype was attempting a landing when the test flight live stream feed paused momentarily before cutting to a loud bang and debris falling from the sky. Footage shows foggy, dark conditions around the crash scene with debris flying around the landing pad.

This was the fourth high-altitude flight test of the Starship prototype.

The SN11 is a prototype for Elon Musk’s Starship Mars rocket, which is being developed to take people to the red planet.

The immediate cause of the explosion was unknown. After the explosion, NASA said the prototype had “experienced an anomaly during the landing sequence.”

“Looks like engine 2 had issues on ascent & didn’t reach operating chamber pressure during landing burn, but, in theory, it wasn’t needed,” Musk said on Twitter. “Something significant happened shortly after landing burn start. Should know what it was once we can examine the bits later today.”

The four previous models have all exploded at various points in the launch and landing process. The SN11’s predecessor, the Starship prototype SN10, exploded moments after a successful landing earlier this month.

Prior to that the SN9, exploded in spectacular fashion in early February – “belly-flopping” onto the launch pad and immediately blowing up.