First responders in the Comox Valley say a man who apparently plummeted off a 24-metre railway trestle Monday night is lucky to be alive.

People passing by the historic railway trestle next to Trent River found the man laying underneath the structure at around 8:40 p.m., according to officials.

"He didn't look that well. I saw head injuries, leg injuries. Paramedics were worried about internal injuries and they wanted to get him out of there as quickly as possible," said Cumberland Fire Chief Mike Williamson.

Search and rescue crews performed a rope rescue to transport the victim from the riverbed up a 45-metre slope to the railway.

He was then transported about half a kilometre to a waiting ambulance.

First responders said they were astonished that the man was still alive after falling such a long distance.

"I'm absolutely amazed that he's alive. I'm not even positive he did fall from the top but if he did, it's a miracle he's alive," said Wiliamson.

Police say they're not sure how long the man was lying next to the river bed for before he was found.

There was no update on the man's condition Monday but authorities say he was conscious, breathing and able to speak with police at the scene.

He remains in hospital with serious injuries.

The matter is not considered suspicious and police are no longer investigating.