The space plane developed by Virgin Galactic crashed Friday after suffering an “in-flight anomaly” during a powered test flight over California.
“All our thoughts are with the families of everyone affected by this tragic event,” Branson wrote in a blog post.
“Space is hard – but worth it. We will persevere and move forward together,” he added.
One pilot died and the other was seriously injured when ‘SpaceShipTwo’ exploded.
SpaceShipTwo was designed to carry two pilots and six passengers on sub-orbital space flights.
The sub-orbital flight has been under development at the Mojave Air and Space Port in the desert, north-east of Los Angeles.
Virgin has planned its commercial launch in 2015 and has taken more than 700 flight bookings at $250,000 each, with Branson pledging to travel on the first flight, BBC reported.
The US National Transportation Safety Board will soon begin investigation, officials said, adding that the US Federal Aviation Administration is also investigating the incident.