An improvised explosive device thrown into a crowd at a Red Cross festival in Umphang district of Tak province in northern Thailand has killed three people and injured at least 39. The incident happened late on Friday, around 23:30 p.m. local time, near the concert stage where spectators were enjoying a performance. 

Thai Prime Minister Patongtarn Shinawatra responded quickly to the tragedy, ordering the national police and local authorities to arrest those responsible as soon as possible. She also ordered assistance to the victims and families of the dead, medical expenses and compensation. 

"The Prime Minister has ordered increased security measures at festivals across the country, including checks for hazardous materials, to prevent such tragedies from happening again," " said government spokesman Jirayu Huansab.  

Deputy Prime Minister Phumtham Vechayachai confirmed that a suspect had been detained, local media reported. He ruled out terrorism, suggesting that the incident could have been the result of a conflict between youth groups. 

Early Saturday morning, police in Tak Province said they had arrested two young men believed to be connected to the incident. They are being held for questioning. 

Authorities are continuing their investigation to determine the exact number of casualties and the motives behind the attack. Security measures have been stepped up across the country in the wake of the incident, especially at public events.