JOHANNESBURG (Reuters) - Angry commuters set fire to two trains in South Africa's capital Pretoria after severe storms disrupted rail services, SAPA news agency reported on Wednesday.

Train services in Pretoria were brought to a standstill after the signalling system broke down and a backup system was struck by lighting, rail operator Metrorail said.

A severe thunderstorm wreaked havoc in large parts of Pretoria on Tuesday, flooding homes and causing severe damage.

Commuters became impatient with the delays, setting fire to two trains as the rail operator tried to organise busses to ferry passengers to their destinations.

Four train coaches were torched and damage amounting to millions of rand was caused to an overhead electricity cable.

"Metrorail condemns the behaviour of commuters following delays caused by the storm -- which it had no control over," SAPA quoted Metrorail spokeswoman Thokozani Zithashe as saying.