His deputy and the Defence Minister, General Prawit Wongsuwan, reiterated that the incident had nothing to do with the ruling junta's third anniversary in power next Monday.
"There had not been any indicator [of potential trouble beforehand] and it was not an attempt by any group," Prawit said. "The police already explained everything and they are always working."
On Monday, police said the explosion was caused by gas pressure building up inside the PVC pipe of an advertising sign. Two women were slightly injured.