Tragic warning given just moments before three friends died as selfie shows they missed heartbreaking detail

Three American teenagers were given a warning just moments before a tragic accident cost them their lives.

In 2011, 13-year-old Savannah Webster had decided to join her older sister Kelsea, 15, who was hanging out with her friend Essa Ricker, also 15, by the Covered Bridge Canyon train crossing, located in Utah's scenic Spanish Fork Canyon - less than an hour's drive south of Salt Lake City.

As many of us did back in the day, the trio posed for pictures together to document their day.

Savannah, known to friends and family as Savy, even posted on Facebook: "Standing right by a train ahaha this is awsome!!!!"

Kelsea Webster, Essa Ricker and Savannah Webster posed for a selfie just seconds before the tragedy (Union Pacific/Essa Ricker/Kelsea Webster/Savannah Webster)

It is understood that the teens had planned to pose for a picture as a train rushed past the tracks in front of them, but they hadn't realized that there was a second train hurtling towards them from behind.

The one harrowing photo in question depicted the three girls taking a selfie slightly off the tracks, but not far enough as to not be struck by the train - which was traveling at an estimated 39mph.

In the background, you can see the eastbound Union Pacific train locomotive approaching them, with train conductor John Anderson operating the machine.

Reflecting on the traumatic moment his train ploughed into the girls, he recalled issuing them a warning as he chimed the train's horn.

The train's conductor opened up about the ordeal (Getty Stock Image/Monty Rakusen)

He, alongside the train's engineer, Michael Anderson, also leant out the window to yell at the girls to move, but tragically to no avail.

"They were in their own little world," explained John, as he spoke with Union Pacific.

"We watched in horror as we got closer. We saw them for about 12 seconds until they disappeared from our sight and the train continued moving forward."

Kelsea and Essa were killed instantly.

After hopping off the train, John and Michael rushed to the scene where they found Savannah still alive.

Speaking about the moment he held Savannah's hand, John added: "I told her everything would be okay and she relaxed a little. I hoped she would make it and for some reason I really thought she would."

Savannah later passed away in hospital after doctors advised her family that the brain injuries she sustained were 'too great', and so they switched off her life support machine.

If you have experienced a bereavement and would like to speak with someone in confidence, contact The Compassionate Friends on (877) 969-0010.