SpaceX's Texas test pad experienced an unexpected explosion, flames, while testing a Starship rocket booster prototype

• SpaceX was testing a prototype of its Super Heavy rocket booster in Boca Chica, Texas, on Monday.
• The booster engines appeared to spew flames, then a loud explosion sounded, shaking distant cameras.

A roaring explosion ripped through SpaceX's rocket testing facilities in Boca Chica, Texas, on Monday.

The company was running a test of the Super Heavy booster, which it's designing to someday push its enormous Starship rocket into orbit around Earth. The system is the keystone of CEO and founder Elon Musk's plan to build an independent settlement on Mars.

At about 4:20 p.m. CT, flames burst from the engines and an explosion sounded in the air, shaking cameras that were recording the test from a distance.

NASASpaceflight captured the incident in a livestream of the test. The NASASpaceflight commentators, who meticulously track SpaceX's plans and activities, said that the explosion was unexpected. SpaceX had not sent out the notices that it normally publishes ahead of an engine test-fire.

The booster prototype, called Super Heavy Booster 7, appeared to be in one piece after the incident. For more than an hour following the explosion, however, black smoke spewed from the area of the test pad, visible in the livestream.

It was not immediately clear what caused the explosion or the smoke.

Musk initially gave an ambiguous response to a Twitter user who asked if the incident was planned.

"Yes. Booster engine testing," he said.

However, it was unclear whether Musk was referring to the test in general, or if the size and force of the explosion was expected. Musk later deleted that Tweet.

He then tweeted, "Yeah, actually not good. Team is assessing damage."

SpaceX did not immediately respond to a request for comment from Insider. The FAA did not immediately respond to a request for comment asking if they will investigate the apparent explosion.

SpaceX has said that it planned to fly a Starship rocket into orbit aboard a Super Heavy booster as early as July, Insider previously reported. However, the company has not yet completed all the actions mandated by a recent review from the Federal Aviation Administration.

Monday's test was one of many that the rocket booster must complete successfully in order to fly safely.

This is far from the first fiery explosion at SpaceX's south Texas facilities, which are intended for early rocket prototype testing. The first four Starship prototypes that the company launched from its Texas site exploded after soaring a few miles high. On the fifth attempt, the prototype flew, landed, and cooled down in one piece.