Virtually everywhere in the city “ended up with a covering of a rather thick, granular, sand grain that just landed on everything,” Valerie Bates, a Port Isabel spokeswoman, said in an interview. Images posted to social media showed residents’ cars covered in brown debris.

A window shattered at a fitness gym, its owner, Luis Alanis, said. Mr. Alanis, who was at home at the time of the launch, said he felt “rumbling, kind of like a mini earthquake.” He estimated that the window would cost about $300 to fix.

Closer to the launch site, large pieces of debris were recorded flying through the air and smashing into an unoccupied car. Louis Balderas, the founder of LabPadre, which films SpaceX’s launches, said that while it was common to see some debris, smoke and dust, the impact of Thursday’s liftoff was unlike anything he had ever seen.

“There were bowling ball-sized pieces of concrete that came flying out of the launchpad area,” Mr. Balderas said. The blast, he added, had created a crater that he estimated was around 25 feet deep.

In a statement posted to Facebook, the city of Port Isabel said that the emergency management division of Cameron County had confirmed the dust “was sand and soil from near the SpaceX launch site that was lofted into the air by the force of liftoff.” A spokeswoman for the county’s emergency management division said that all questions regarding the dust from the explosion should be directed to SpaceX.