The shooter or shooters were at large amid an active investigation, Pearland police said in a statement, NBC News reported.
Two of the victims were minors, police spokesperson Chad Rogers said at an evening news conference. The police department later said on X, the platform formerly known as Twitter, that "one of the juvenile victims has died of their injuries."
All five victims had been hospitalized, according to the department's statement. Their conditions were unavailable.
Police responded to Cole's Flea Market in Pearland, a city about 21 miles south of Houston, based on a 5:34 p.m. report of shots fired, the department said.
Rogers said the shooting was the result of issues between two people at the location and wasn't random. It's possible there were two shooters, he said.
"This started because there was a disturbance between two individuals at the flea market that resulted in gunfire," the spokesperson said, noting the information was preliminary.
"It does not appear to be any kind of targeted attack on the flea market," Rogers added.
Houston police and Harris County authorities were assisting Pearland police with their investigation and search for any suspects, NBC affiliate KPRC of Houston reported.
No suspect description or possible vehicle information was immediately available.