A runner at Sunday’s Santa Barbara Half Marathon struggled toward the finish line while experiencing a deep fog — then suddenly woke up in a medical tent.

Nineteen competitors were hospitalized after the event, prompting a police investigation into what caused their “unusual symptoms.”

One mom, who requested anonymity, told The Post her daughter was well prepared for the race and runs regularly but near the finish she got sick.

“You can see on her Garmin, [she] went from a really decent pace to a crawl,” she said. “She has no memory of the finish line. She said she saw it and it felt like she was running through Jell-o.”

Her daughter’s next recollection was waking up in the medical tent, according to the mom.

“She then woke up in the med tent, scared and sick, and just sounds like a horrifying experience. And I, it just broke my heart. It makes me sick.” she said.

Her daughter’s girlfriend joined her, and they ended up going to the hospital, the mother said. “I talked to her from the hospital and she was just really thrown,” she said.

The mom said her daughter is now doing well, but the experience has left the family shaken. “It just broke my heart. It makes me sick,” she said.

She questioned explanations attributing runners’ medical emergencies to heat or inadequate preparation, saying her daughter had trained extensively.

Race organizers believe the runners suffered from heat exhaustion, but unverified rumors circulating on social media suggested a water station along the course may have been spiked.

The mother also believes contaminated water at an aid station could have been responsible, but didn’t have evidence for it.

Police said the cause remains undetermined.

Santa Barbara Half Marathon Event Director David Monico told The Post their medical team “treated numerous runners for dehydration and overheating both on the course and at the finish line.”

“Some of those runners were transported to local hospitals for further treatment and enhanced care,” he said.

“Our team’s goal, as that of any endurance event production, is to get people home safely. We hope that each of the participants return to their family and friends safely, but at this moment we do not have any additional information.”

Monico added that his organization didn’t have more information to provide on the runners that sought medical treatment.

Temperatures in Santa Barbara reached 86 degrees on Sunday, and Monico said hospitalizations are not unusual during races, particularly when temperatures are high.

The symptoms of woman’s daughter alone don’t establish what caused the episode. “We always drink from the water stations, and I’m just — the thought of this is so scary,” she said.

The mom also criticized race organizers’ handling of the situation, describing a conversation with a race executive as callous and questioning why organizers were already promoting next year’s event.

“I feel that there’s a lack of responsibility on the people that had planned this race,” she said.

“They’re so concerned about covering their own butts and not worried about these runners that ended up in the hospital. You know who are out there on their dime, on their paid to be there, and so it’s just so upsetting.”

The family has participated in races together for years, the mother said, making her daughter’s experience particularly unsettling.

“My concern is what incredibly dangerous thing just happened, and what if it happens again somewhere else?” she said. “What if someone was pregnant? What if someone got hurt?”

Santa Barbara Police Lt. Ethan Ragsdale said investigators were looking into “suspicious circumstances” surrounding reports of runners seeking “medical treatment for unusual symptoms” after the race.

Meanwhile, speculation continued to spread across social media that someone had tampered with water stations along the course.

Authorities have not confirmed those allegations, and there is no verified evidence that the runners were deliberately exposed to any substance.

Emergency personnel responded to multiple locations along the marathon route, including the intersection of State and Cota streets, between 9:40 a.m. and 10:45 a.m.

Santa Barbara City Fire Department Battalion Chief Cory Cloud told Noozhawk that 12 people were transported to Santa Barbara Cottage Hospital and another three to Goleta Valley Cottage Hospital.

Four others made their own way to hospitals.

Cottage Health spokesperson Cristina Cortez confirmed emergency departments experienced “a larger than expected number of emergency visits” connected to the race.

“This morning 19 participants arrived at Cottage EDs, a number of them with similar symptoms of undetermined cause. We are working to determine whether this is due to the heat or other factors,” Cortez said.

Authorities have not disclosed the specific symptoms experienced by the runners or the severity of their conditions.

“There is no specific action recommended for the general public at this time,” Ragsdale said. “However, participants who feel unwell should seek medical attention and follow guidance from healthcare professionals.”