SpaceX Falcon 9 rocket was captured exploding on its pad during a test on Thursday September 1, 2016,  at Cape Canaveral Air Force Station.

The scene which left no one injured was described by witnesses who reported seeing a fireball, feeling shock waves in buildings several miles away at Kennedy Space Center and seeing a plume of smoke rising from Launch Complex 40 just after 9 a.m and hearing multiple explosions.

super xSpaceX CEO Elon Musk said around 1 p.m. that an issue came up while the rocket was being fueled for a testing of its main engines, part of preparations for a planned early Saturday launch of a commercial communications satellite in which Facebook had a stake.

From his tweet, Musk said on Twitter. “Originated around upper stage oxygen tank,”  he further tweeted,  “Cause still unknown. More soon.”

Its said Facebook planned to use some of the satellite’s capacity to expand its Internet.org initiative in Africa. CEO of Facebook Mark Zuckerberg was in Africa promoting the satellite’s benefits ahead of the upcoming launch.

Responding to the situation, Mark said in a post on his Facebook page.

That failure was attributed to a broken strut that caused the upper-stage oxidizer tank to rupture, resulting in the rocket breaking apart.

SpaceX returned the Falcon 9 to flight six months later, and had completed nine successful launches since December, including eight by an upgraded, more powerful version of the rocket.

The company has made headlines during that period for landing six Falcon boosters, part of Musk’s effort to develop reusable rockets.

While the cause of the latest mishap is unknown, it almost certainly will result in months of delays to a SpaceX launch schedule that was already behind, causing consternation among its backlogged customers.

In addition to an investigation into any problems with the rocket, it was not immediately clear if the launch pad suffered significant damage.

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