Muangthong came from a goal behind to seal a 3-1 win that lifted them to third spot in the table ahead of League Cup winners BEC Tero Sasana.
There was no sign of trouble at the final whistle at SCG stadium as Singhtarua fans, known for their rowdy behaviour, left the venue peacefully. But outside, a large group of away supporters gathered at a nearby intersection and began attacking Muangthong fans as they passed.
A melee ensued, with Muangthong supporters retreating to the stadium and attempting to block Singhtarua fans from re-entering the venue. Those injured in the clash were taken to the first-aid room inside the ground for treatment.
It took more than an hour and a half before military and police moved in to restore order, arresting Singhtarua troublemakers and taking them to Pakkret police station.
But the trouble didn’t end there. Another group of Singhtarua fans found a way into the ground through the car-park gate behind and vandalised the club’s store. More away supporters also gathered at the intersection again and made it clear they would attack any Muangthong fans they identified in passing cars.
It took officials until midnight to restore control by making more arrests and dispersing Singhtarua fans.
Many Muangthong supporters were clearly unhappy with the police, complaining they had been too slow to step in. One fan said he asked for help from a police officer only to be told: “How can I help you? I will get a beating from them.”