CHULA VISTA (CNS) - Authorities have identified a man who died when he crashed while riding a motorcycle with his wife late Thursday near Lower Otay Lake, and online tributes have identified him as a Camp Pendleton Marine.

Promlikhit Khamkhong, 27, was pronounced dead just before 10:30 p.m Thursday after crashing near Otay Lakes Road, just east of Wueste Road, officials from the county medical examiner's office said. Authorities said the cause of death was blunt-force injuries to his spine near the base of his skull and to his upper back.

Khamkhong was riding with his wife seated behind him when he failed to negotiate a curve on westbound Otay Lakes Road, the medical examiner's office said. The motorcycle left the roadway and sent the couple plunging down a steep embankment.

"Unable to find (Khamkhong), his wife was able to crawl back up to the roadway and flagged down a passing motorist for help," medical examiner's officials said.

In a post on Instagram, Khamkhong's wife, Carolina, said she was "heartbroken" and "in disbelief."

"Last night I lost my husband in a motorcycle accident," she wrote under a photo of the couple with their pre-teen son. "He is so selfless that he pushed me off the motorcycle before we hit the bottom of the embankment. I miss my best friend, my soulmate, my everything."

She then recounted the crash and the aftermath.

"I couldn't find you, I was calling out for you but I couldn't hear you," she wrote. "I know I had to get help so I climbed up the hill, I kept falling but I needed help to find you. I am so grateful that after 5 minutes of cars driving by and not stopping, someone finally did. But it was too late."

The medical examiner's office said emergency crews found Khamkhong unresponsive and showing no signs of life, and he was pronounced dead at the scene.

An online photograph from 2014 identified Khamkhong as a hospital corpsman, Petty Officer 3rd Class, with the 3rd Battalion, 5th Marine Regiment, 1st Marine Expeditionary Force. The infantry battalion, nicknamed "Darkhorse," is based at Camp Pendleton.

The battalion's informal Facebook group "The Boys of 3/5," posted a link to a story about Khamkhong's death and said: "Sadly, we have lost Darkhorse Devil Doc, Promlikhit Khamkhong, in a motorcycle accident. Rest easy."