U.S. federal aviation regulators said on Friday they are grounding SpaceX's Falcon 9 rocket after an engine failure during Thursday's launch of a batch of Starlink satellites.

Falcon 9 rocket experienced a rare and troubling setback Thursday night as it attempted to lift off 20 Starlink internet satellites to orbit from Vandenberg Space Force Base in California.

Approximately an hour after the takeoff, the rocket's second stage failed to reignite, and instead deployed the satellites in a dangerously low orbit at risk of burning up in the Earth's atmosphere.

The U.S. Federal Aviation Administration (FAA) required an investigation into the Falcon 9's malfunction, though "no public injuries or public property damage have been reported."

FAA said that the rocket will be grounded until the issues have been resolved and it is determined that there is no threat to public safety.

In a statement on social media X, SpaceX said that during Thursday's launch, "the second stage engine did not complete its second burn."

"As a result of the incident, the Starlink satellites were deployed into a lower than intended orbit," it added.

Elon Musk, SpaceX founder and CEO, posted on X that the engine failed "for reasons currently unknown. Team is reviewing data tonight to understand root cause."

Thursday's incident occurred on Falcon 9's 354th mission and marks its first failure since 2015, when the rocket exploded on a launch site in Florida.