A runner who gained an online following for his love of Disney collapsed and died following Disneyland's Halloween Half-Marathon in Southern California on a day when temperatures soared into the triple digits. 

Bobby Graves, whose online handle was @calebgtravels, went into cardiac arrest after he ran a little over 13 miles through the Anaheim amusement park on Sunday.

Marathon workers noticed Graves grab his chest after he crossed the finish line at 7 a.m. and quickly rendered aid, calling for paramedics stationed nearby, Anaheim police Sgt. Matt Sutter said in a statement to USA TODAY on Thursday. 

Graves, 33, was in “full cardiac arrest” as Anaheim Fire & Rescue personnel began trying to save his life, according to Sutter.

Graves was rushed to a local hospital for treatment but died about an hour after he arrived. Graves’ cause of death will be determined by the Orange County Coroner’s Office. Sutter was “not aware of any underlying or previous medical issues that Mr. Graves may have been dealing with.” 

Graves' friends and family confirmed his death on Facebook, asking the public to give those impacted by the loss "the space and opportunity they need to make the upcoming arrangements necessary for such an incredible loss, and to join with us in prayer for peace that surpasses all understanding."

‘Excessive heat warning’ issued through race weekend

The day before Sunday's race, Graves posted a video in which he talked about how hot it was while he was on a dog walk and that he passed out from heat exhaustion, adding: "I really hope I get through the race tomorrow morning."

The haunting video was no longer available online as of Wednesday morning. Southern California experienced record temperatures over the weekend, when heat advisories were in effect across the state.

Matt Benz, a senior meteorologist at AccuWeather, told USA TODAY on Thursday that a heat advisory was in effect for the Anaheim area on Sunday. When Graves crossed the finish line at 7 a.m., the temperature was around 73 degrees and peaked at 108 degrees by noon, Benz said.

When heat advisories are in effect, health officials warn people to limit outdoor activities.

'Deeply saddened' by runner's death, Disney says

Disneyland spokesperson Jessica Good said in a statement that the company is "deeply saddened by this tragic loss, and our hearts are with Caleb’s family and loved ones during this difficult time."

Graves spent a lot of time at Disneyland, using social media to document various experiences, including running events, he has participated in as a park visitor. He grew a following online that way, posting Disneyland and Universal Studios Hollywood content to an audience of about 30,000 people across TikTok and Instagram.

Graves also made another video before the race, showing him at the half marathon expo, where he "grabbed his bib, shopped a little merch and got hype for the Sunday race!"

"If you’re running this weekend, remember it will be HOT!" Graves wrote in the caption. "Stay hydrated and listen to your body. Good luck to all the runners!"

Graves described himself as a writer, director, screenwriter, and producer who grew up in Stephenville, Texas, a small town just outside Dallas, according to an his website. He most recently was living in Southern California.

"In his spare time, Caleb likes to run, travel, and eat donuts," the bio reads.

He also worked as an associate at Wilson Sonsini Goodrich & Rosati, a law firm headquartered in Palo Alto, California. Graves specialized in "entertainment, intellectual property, and commercial litigation."

How to stay safe running in hot weather

Here are some tips for running in hot weather, courtesy of Road Runners Club of America:

• Be Alert
• Avoid dehydration
• Prehydrate
• Carry water
• Understand heat index dangers
• Know the signs of heat illness
• Know the signs of heat stroke
• Get help immediately if you suffer heat stroke
• Check with your doctor
• Dress for the weather
• Apply sunscreen