SEREMBAN, MALAYSIA - Indian national Sunil Kumar will never forget his first trip to Kuala Lumpur.

The 34-year-old from Madras, who works in Singapore, took advantage of the Workers Day break for a trip to Malaysia with his wife Madhu Bhandari, 33, and three-year-old son.

The family had boarded the Singapore-bound train at 2.15pm from Kuala Lumpur and were enjoying the comfortable ride when their coach at the end of the train began to shake.

"There were two big jolts. Suddenly, we were flung forward and the train stopped," he said.

"I am grateful that my wife and son are safe. I must admit that it was a scary experience."

Singaporeans Winston Carter Ong, 60, and his son Terence, 35, who were in the front coach which turned turtle, said people were thrown off their seats.

"The train swerved sharply and before we knew it, we were upside down. When the train stopped abruptly, I saw a Chinese woman bleeding from her head," he said.

Terence, who is now living in New Zealand and was visiting Kuala Lumpur after 15 years, said it was a frightening experience.

"I was supposed to be heading to China for a holiday on Monday but that trip may have to be postponed. I am grateful to God as both my dad and I are safe," he said.

Australian Graham Nicholas, 54, who was travelling with his wife, said he was asleep when the incident happened.

"All of a sudden, there was a loud bang and the coach began to shake but we could also feel that the driver was trying to apply the brakes as there was a deafening screeching sound," said Nicholas.

"We did not know that the coaches in front had derailed until we came out to check why the train had stopped," he said.

Haja Maideen Abdul Rahman, 62, who was going to Johor Baru, said the incident was over within seconds.

He said the passengers were screaming when the train began to go down the slope and into the river.