BANGKOK (AP) — Thai police on Saturday said two suspects were in custody as authorities investigated a bombing in the north that killed at least three people and injured dozens of others.

An explosive device was thrown into a crowd during an outdoor performance at an annual festival in Umphang town in Tak province, which borders Myanmar, on Friday just before midnight, according to the Association of the Umphang Rescue Groups.

Local police said at least 48 people were injured and that police have not yet pressed charges against the suspects as the investigation is ongoing.

Thanathip Sawangsang, a spokesperson for the Defense Ministry, told The Associated Press that local police said there was a fight between rival groups of men before the explosion and that there was no wider security threat. He said the forensic evidence showed that the explosive device was a homemade bomb.

Tak province has a heavy military presence in its border areas, including in Umphang.

Prime Minister Paetongtarn Shinawatra expressed her condolences to the victims and their families, and ordered security personnel and relevant agencies in the area to investigate and help those who have been affected, said government spokesperson Jirayu Houngsap.