A prototype version of SpaceX’s next-generation rocket caught fire last night following an engine test in Boca Chica, Texas. About four minutes after SpaceX briefly ignited the vehicle’s engine, a second small explosion engulfed the rocket in flames for a few seconds — seemingly by accident. The fire was quickly extinguished, but the incident may postpone the first big flight of the vehicle.

The hardware that caught on fire is the test model of SpaceX’s next big rocket, the Starship: a massive spacecraft the company is developing to take people and cargo into deep space. SpaceX is building multiple versions of the rocket at the company’s test facilities in Cape Canaveral, Florida and Boca Chica. These vehicles are meant to try out the Starship design and eventually test its capabilities in space.

The test rocket in Boca Chica is tasked with showing off the prowess of SpaceX’s new engine, the Raptor, which was developed specifically for Starship. Equipped with one Raptor engine on its underside, the test vehicle is set to perform a series of “hop” tests in the weeks and months ahead. During these events, the vehicle’s engine will ignite, taking the rocket up to an altitude high above the Earth. It’ll hover there for a period of time before using its engine to land back on the ground. It’s all meant to test the vehicle’s capability to launch from and land on Earth — as well as other planets.

The test vehicle, nicknamed Starhopper, has already seen a little bit of action. In April, SpaceX ignited a Raptor engine underneath the rocket for the first time. During that test the vehicle was tethered to the ground during that ignition and subsequent firings, so the rocket hasn’t seen any air yet.

SpaceX had been planning to perform the first hop test this week. Last night, ahead of the hop, SpaceX ignited the Raptor engine briefly while Starhopper was constrained, to see if the hardware was ready. But just moments after a seemingly successful ignition, the rocket lit up again in a fireball and had to be doused.

SpaceX did not confirm whether or not the second explosion was indeed an accident, but according to locals, there are no more road closures planned around the company’s site. That indicates testing is no longer scheduled for the rest of the week. Photos of Starhopper taken this morning show seemingly minimal damage to the vehicle.