One of the Thais was injured in the fight, according to a friend of a victim, who added that the two factions had quarrelled in the past, although this was the first time it had led to physical violence.
Lumphini station chief Pol. Col. Yingyos Suwanno said officers were dispatched to the location to stop the fight, ensure public safety, and invite all parties to an interview at the station.
Investigators are interviewing the two groups as well as witnesses to determine how the fight started. They will also check the travel documents of non-Thais to ensure that no immigration laws have been broken.
About 100 people, most of them Thai transgender women, flocked to the station on Monday to ask for an update on the incident. One of them told The Nation that they would like police to increase patrols in Soi Sukhumvit 11/1 to prevent an assault on Thai transgenders.