Bangkok Mass Transit System (BTS) electric train services in Bangkok were disrupted when train No.6 broke down at Mor Chit station about 7.50am, reports said.
The malfunctioning train blocked the the track, preventing BTS putting all 30 trains into use and resulting in long delays.
Thousands of peak-hour commuters were stranded at all stations waiting for their train.
The problem was not solved until train No.6 had been removed and all the other trains put into service.
Skytrain services returned to normal from about 8.50am.