An unmanned SpaceX rocket carrying supplies and the first-of-its-kind docking port to the International Space Station broke apart Sunday shortly after liftoff. It was a severe blow to NASA, still reeling from previous failed shipments.

The accident occurred about 2 1/2 minutes into the flight from Cape Canaveral, Florida. Pieces could be seen falling into the Atlantic. More than 5,200 pounds of space station cargo were on board, including the first docking port designed for future commercial crew capsules.

“The vehicle has broken up,” announced NASA commentator George Diller. He said it was not clear how the disaster occurred or even when the rocket actually failed. Data stopped flowing from the Falcon 9 rocket around 2 minutes and 19 seconds, he said. No astronauts were on board.

The rocket appeared to break apart while traveling at 2,900 mph, about 27 miles up.

The California-based SpaceX was trying to figure out what happened, noting that everything appeared to go well in flight until the rocket went supersonic.

Losing this shipment – which included replacements for items lost in two previous failed supply flights – was a huge setback for NASA in more than one way. The space agency is counting on private industry to transport cargo – and eventually astronauts – to the orbiting lab. SpaceX is one of the contenders.

The seven previous SpaceX supply runs, dating back to 2012, had gone exceedingly well.

This is the second failed station shipment in a row and the third in eight months.

In April, a Russian cargo ship spun out of control and burned up upon re-entry, along with all its precious contents. And last October, another company’s supply ship was destroyed in a launch accident.

This Dragon had been carrying replacement food, clothes and science experiments for items lost in those two mishaps.

The three space station residents were watching the launch live from orbit.

“Sadly failed,” space station astronaut Scott Kelly said via Twitter. “Space is hard.”

The space station crew is in no immediate trouble because of this latest loss. Late last week, NASA’s space station program manager, Mike Suffredini, said the outpost had enough supplies on board to make it to October or so.

Russia expects to take another crack at launching supplies on Friday from Kazakhstan.

SpaceX – led by billionaire Elon Musk, who also heads up electric car maker Tesla – is one of two companies hired by NASA to start ferrying American astronauts to the space station as early as 2017. The other contender is Boeing.

Musk noted via Twitter that the rocket “experienced a problem shortly before first stage shutdown.” The company had hoped to land the first-stage booster on an ocean platform, off the north Florida coast, in a test of rocket reusability. Previous efforts had failed.

Launch spectators lining the beaches near Cape Canaveral were confused, at first, by the unexpected plumes in the sky.

“It looked fine until it was almost out of sight. And then, a poof of smoke,” said Whitney Jackson of Palm Beach, Florida, watching with her family. “Everyone was cheering and clapping. No one knew it meant failure.”

Sunday, by the way, was Musk’s 44th birthday.