Police said a suspect, who is a minor, was apprehended on Tuesday less than an hour after the first reported gunshots at the Siam Paragon Mall.
One person had been killed and six were injured, according to Yutthana Sretthanan, director of Bangkok’s Emergency Medical Center.
The shooting prompted authorities to shut access to the nearby Siam elevated train stop, preventing commuters from exiting the transit station as the evening rush hour began and intense rain pounded the city.
First responders could be seen entering the mall as sirens wailed outside.
Witnesses said crowds of people left the building, one of several shopping centres in the area popular with tourists and well-heeled Thais alike.
The incident happened days before Thais were planning to mark the anniversary of a grisly gun and knife attack at a rural daycare centre that killed 36 people, most of them preschoolers, on October 6, 2022.