Deputy Police Commissioner General Pol Gen Somyos Pumphanmuang said Saturday that the explosion at the Rama IX Intersection Friday night might not be related to politics.
He said the explosion occurred at 7:05 pm before the lifting of the curfew.
Police found that the bomb was a Russian-made RDG5 grenade. Somyos said someone might discard the grenade there and a car might accidentally run over it.
He said it was also possible that the explosion was caused by a fight between local rival gangs of teenagers.