Five people were killed and eight wounded in a gunfight between rival gangs at Mor Chit 2 Bus Terminal early Wednesday morning, police said.
After an earlier argument, a fight broke out at about 12.20am between a group of motorcycle taxi drivers and people living near the bus terminal on Kamphaeng Phet 2 Road.
Both sides were armed with an assortment of weapons including knives, steel pipes and guns, and started to shoot at each other.
The shootout initially left two people dead. Another three people later succumbed to their injuries in hospital.
The five dead were motorcycle taxi drivers Phutthisak Klongklaew, 24, and Attachai Thantachote, 21, who died at the scene, and locals Anusorn Moadkula, 27, Phayu Sae-jew, 25, and Cherdchai Chomphucharoen, 42, who died in hospital.
Six of the eight injured remain in hospital.
Pol Col Charoen Srisasalak, deputy chief of the Metropolitan Police Bureau's Division 2, said earlier in the evening a group of young people from Kamphaeng Phet 2 Road area went to a game store inside a terminal building.
They made a lot of noise which upset members of a motorcycle taxi queue operating near the store. Pol Col Charoen said the groups were rivals and had fought several times. They harangued each other which led to fist fights.
The Kamphaeng Phet group left and returned late at night with more than 15 men, some armed with guns. They saw the taxi drivers drinking and celebrating New Year near the queue and a fight broke out again. Witnesses said they heard many gun shots.
Police later found more than 30 spent cartridges and bullets from .22-calibre pistols and 9mm guns. At least five handguns were involved in the showdown, Pol Col Charoen said.
He said Bang Sue police were able to identify the people involved in the fight and will question witnesses before seeking arrest warrants.