Police are gathering evidence to support their request for arrest warrants for 13 more suspects in a gunfight on Sunday that killed an Indian tourist and injured four other people in the Pratunam area of Bangkok.
Two Indians, a Lao national and two Thais were caught in the crossfire in the gun battle near the Watergate Pavilion shopping mall.
Arrest warrants have already been issued for 14 suspects, nine of whom are now in police custody.
Khwan Krataithong, one of the detained suspects, denied any wrongdoing, police said.
He claimed he visited the area where the shooting occurred on Sunday but was not there when it took place, police said.
Sonram Phuphonphan, another suspect detained previously in Chumphon province, is believed to belong to the same gang as Phonthep Phumphuang, who was arrested in the same province, police said.
Investigators were still unable to determine who fired an AK-47 assault rifle during the shootout.
A row broke out between two groups in a car park near the shopping mall where foreign tourists were waiting to board a coach.
As they were firing at each other, stray bullets hit the five victims. Reports said the melee broke out next a pool hall.
On Thursday, acting Tourist Police Bureau commissioner Terapon Kuptarnond held a press conference during which two cheques of 1 million baht each were presented to the family of the slain Indian tourist as compensation.
The cheques were from the Ministry of Sports and Tourism and from an insurance company retained by the government.
Basant Gakhreja, 45, received the cheques in a tearful presentation by Pol Maj Gen Terapon.