New York CNN Business  — 

Thick plumes of smoke rose over a SpaceX facility in Florida during a test fire of a Crew Dragon spacecraft on Saturday. If the issue was serious, it could derail plans to fly astronauts aboard the capsule later this year.

SpaceX said the craft was undergoing a “series of engine tests” at a facility in Cape Canaveral, and something went wrong during the final stretch. SpaceX will work with NASA to determine what caused the issue. No injuries were reported.

“Ensuring that our systems meet rigorous safety standards and detecting [issues] like this prior to flight are the main reasons why we test,” SpaceX said in a statement.

Crew Dragon is already overdue, and more delays could make things tricky for NASA. The United States has not had the technology to fly humans to orbit since the space shuttle program ended in 2011. Meanwhile, NASA has paid Russia about $80 million per seat to send astronauts to the International Space Station aboard Soyuz capsules — a fact that isn’t very popular in the halls of Congress.

NASA decided to ask the private sector to design and build a new generation of spacecrafts.

SpaceX and Boeing (BA), which is building a vehicle called Starliner, were awarded contracts worth up to $2.6 billion and $4.2 billion, respectively, in 2014. Both capsules were supposed to start flying in 2017, but SpaceX and Boeing (BA) have been hampered with delays.

SpaceX, which was founded by Elon Musk in 2002, beat Boeing to the launch pad by sending Crew Dragon on an uncrewed test flight in March, during which the capsule docked with the ISS for a few days before returning home. That mission appeared to go off without a hitch.

Crew Dragon was scheduled to conduct a key test of its emergency abort system in June. And its first crewed mission, which will carry astronauts Doug Hurley and Bob Behnken, was slated for July, though NASA recently said that timeline was under review.

Boeing is aiming to launch Starliner’s uncrewed test flight sometime in August, potentially putting the capsule on track to fly astronauts by the end of the year.

Federal oversight authorities warned NASA last year that more delays could leave US astronauts stranded if the new capsules were not ready to fly in 2019. NASA had only reserved Soyuz seats through December. But the space agency revealed in February that it would try to secure two more seats — one on a flight that would depart later this year and another on a mission scheduled for spring 2020 — to assure “continuous safe operation and research activity on ISS.”