SINGAPORE - Mr Muhammad Hatin Kamil had one foot over the third rail of the MRT track - which supplies power to trains - when a voice screamed out from behind: "Train is coming! Train is coming!"

The 24-year-old SMRT trainee caught a glimpse of a train hurtling towards him. He saw his friend, fellow trainee Nasrulhudin Najumudin, who was ahead, running desperately towards the walkway.

Mr Hatin pulled his foot back onto the walkway, clinging to the side railing to avoid getting hit.

He looked up to check on Mr Nasrulhudin, only to see the train crushing him, and flinging trainee Muhammad Asyraf Ahmad Buhari into the air.

The men had been part of a 15-strong team sent to investigate a possible fault on Tuesday (March 22), said Mr Hatin.

They had been walking in a single file, with Mr Nasrulhudin, 26, and Mr Muhammad Asyraf, 24, second and third in line respectively behind a supervisor..

Both men were pronounced dead on the scene.

The men had been walking on a 0.5m-wide access walkway alongside the track, facing the oncoming trains, as they were supposed to. Mr Hatin was the fifth person.

He said that high voltage had been detected from a point machine on the track. To inspect the device, the group, which was moving on a maintenance walkway, had to cross over a 'live' third rail to get onto the tracks.

What they did not know was that an oncoming train would soon switch tracks, heading right towards them.

"We didn't realise that there was a train coming towards us from this second track, going to our track, the first track," said Mr Hatin.

"Aysraf's body flew over behind me, like 5m away," he added.

He recounted the horrific accident on Wednesday (March 23), when he and his friends were in a Tampines void deck near Mr Nasrulhudin's home, paying their last respects to him.

The supervisor walking in front of the two victims narrowly avoided the train by jumping onto the walkway and squatting. No one else was hurt.

"This happened right in front of my eyes," said Mr Hatin, choking up at the memory of his friend's death.

"I couldn't think. I went back to the platform, I couldn't do anything."

No one knew a train was coming, he added.

"Our environment up there is different - you wouldn't be able to hear the train coming," he explained, adding that their supervisor had not said anything in the moments before the accident.

"The person in charge knows the system because they are more senior than us. Our job was to observe.

"It's very harsh. I don't know who is at fault."

The two men were buried side by side at the Muslim Cemetery in Lim Chu Kang on Wednesday evening (Mar 23), with around 500 friends and relatives turning up to say their farewells.

SMRT has said that a key safety procedure had not been followed. The rail operator revealed on Wednesday (Mar 23) that the group of 15 technicians, including the victims, had failed to notify a station signal unit that they were stepping back onto the track.

That meant a train travelling at 60kmh on automatic mode was not diverted to an alternate platform or told to stop.

The driver applied emergency brakes when he saw staff on the track, but it was too late.

It was the first time Mr Hatin and Mr Nasrulhudin, who were "best buddies", had been on the tracks during the day. The pair had been on the tracks at night previously, and had also worked together on shifts.

The trainees joined the train operator only in January, and had known each other since their first days on the job.

"He was my best buddy. He was my everything... my work buddy," said Mr Hatin.

"He was always with me; we ate breakfast at 4am together."

Seeing his friend's body laid to rest at the cemetery, Mr Hatin broke down again.