A 44-year-old man who claimed to be a small contractor from Nan province managed to slip into Government House to file complaint with the prime minister.
The man identified later as Chalermkiat Sonnontee was said to hold a ping pong bomb and threatened security guards to keep off as he climbed over fence to the rooftop of the main building which serves as the directorate of the Government House.
The man carried a fabric poster which reads he wanted to seek justice from the prime minister.
Security officials shouted for him to climb down for his safety, but he didn't listen and shower a round object in his hand which was later said to be a ping pong bomb.
The man claimed it was his third time to come to Government House to lodge complaint after he was unfairly treated by local authorities in a bidding for a project.
He claimed he was discouraged from the bidding and said the bid winner is those who have close connection with local authorities.
As authorities tried to convince him to get down for talk there was a sound of explosion indicating a ping-pong bomb was thrown.
The man was later subdued and taken out of Government House after over and hour of talks.
He was escorted to a police station for questioning.
Source: Thai Public Broadcasting Service (Thai PBS)