MBK shopping centre was left in the dark but power had already returned to other areas in Siam Square following a blackout on Friday evening.
Arthorn Sinsawadi, governor of the Metropolitan Electricity Authority (MEA), said that electricity in the areas went out after an explosion at the Pathumwan power station at 6:50pm.
The MEA was investigating the cause of the explosion, he added.
The blackout left people at MBK and malls in the Siam Square area in pitch darkness for about 50 minutes.
The MEA was able to supply reserve power from other stations to Siam Square at 7.30pm in most areas except MBK. The problem forced the shopping centre to close.
Police pressed the MEA to act quickly after the outage because the Pathumwan district was a heavily populated area with many giant malls.
Shoppers leave MBK after the power failed at 6.50pm on Friday. (Photo by Patipat Janthong)