A U.S. spy satellite that was launched from Cape Canaveral, Fla., aboard a SpaceX rocket on Sunday failed to reach orbit and is assumed to be a total loss, two U.S. officials briefed on the mission said on Monday.

The classified intelligence satellite, built by Northrop Grumman Corp, failed to separate from the second stage of the Falcon 9 rocket and is assumed to have broken up or plunged into the sea, said the two officials, who spoke on condition of anonymity.

The satellite is assumed to be "a write-off," one of the officials said.

The presumed loss of the satellite was first reported by the Wall Street Journal.

SpaceX president and COO Gwynne Shotwell later released a statement that read:

"For clarity: after review of all data to date, Falcon 9 did everything correctly on Sunday night. If we or others find otherwise based on further review, we will report it immediately. Information published that is contrary to this statement is categorically false. Due to the classified nature of the payload, no further comment is possible.

"Since the data reviewed so far indicates that no design, operational or other changes are needed, we do not anticipate any impact on the upcoming launch schedule. Falcon Heavy has been rolled out to launchpad LC-39A for a static fire later this week, to be followed shortly thereafter by its maiden flight. We are also preparing for an F9 launch for SES and the Luxembourg Government from SLC-40 in three weeks."

Whoa. You don’t see statements like this every day. Gwynne Shotwell of <a href="https://twitter.com/hashtag/SpaceX?src=hash&ref_src=twsrc%5Etfw">#SpaceX</a> saying in no uncertain terms that <a href="https://twitter.com/hashtag/Falcon9?src=hash&ref_src=twsrc%5Etfw">#Falcon9</a> worked perfectly Sunday night and anyone saying anything to the contrary is spreading false statements and misinformation. <a href="https://twitter.com/hashtag/Zuma?src=hash&ref_src=twsrc%5Etfw">#Zuma</a> <a href="https://t.co/FRd1zfdxHj">pic.twitter.com/FRd1zfdxHj</a> —@ChrisG_NSF

SpaceX plans to conduct an unmanned test launch of its Falcon Heavy some time later this month, which will be the "most powerful operational rocket in the world by a factor of two."

No indication of sabotage

Northrop Grumman built the multibillion-dollar satellite, code-named Zuma, and was responsible for choosing the SpaceX Falcon 9 launch vehicle, both officials said.

An investigation is underway, but there is no initial indication of sabotage or other interference, they said. SpaceX spokesperson James Gleeson said: "We do not comment on missions of this nature; but as of right now reviews of the data indicate Falcon 9 performed nominally."

Space Exploration Technologies Corp, led by entrepreneur Elon Musk, launched its first satellite for the U.S. military with its Falcon 9 rocket in May of last year.