Elon Musk's SpaceX experienced another spectacular setback as another rocket exploded during liftoff.

The unmanned Falcon 9 rocket took off Sunday morning Cape Canaveral, Florida at 10:21 a.m., local time. At two-and-a-half minutes into the launch, at an altitude of about 27 miles, the rocket broke apart. As the AP points out, this is the second launch in a row to fail for SpaceX NASA, and the third since October.

Elon Musk (whose 44th birthday is today—happy birthday!) tweeted that a problem with an oxygen tank was noticed in an initial look at the data, but said a "thorough" analysis would follow. "Space is hard," wrote NASA astronaut Scott Kelly, who is in the midst of a year-long stay at the International Space Station:

According to Space.com, the Dragon spacecraft on the rocket was carrying 4,000 pounds of supplies and scientific equipment for the ISS. While today's failure was a huge loss, there are supply launches scheduled in the coming months, and the three astronauts currently on board have enough supplies to last them until the fall.

Editor's note: An earlier version of this post stated that this is the third launch since October to fail for SpaceX. It is the third NASA resupply mission since October to fail. The post has been corrected.