Sidney Wolfe was covered in blood. It coated her long chestnut-colored hair. It stained her face and arms. It soaked through most of her white floor-length gown, turning the fabric a dark crimson.

That’s how the 20-year-old looked when first responders found her behind the wheel of her totaled Toyota Corolla along a stretch of highway in southern Ohio shortly before 1 a.m. last Saturday, prompting the medics to prepare for the worst.

“Everyone who was a first responder thought I was dead,” Wolfe, an accounting major at Marshall University in West Virginia, tweeted this week, sharing photos of her wrecked car and a grisly selfie.

But not only was Wolfe very much alive after hitting a large deer that jumped in front of her car, she was unharmed, save for a minor bruise on her leg. The copious amounts of blood that had initially alarmed the first responders and a motorist who pulled over to help was makeup: Wolfe was dressed up as Carrie White, the title character of Stephen King’s 1974 horror novel “Carrie.”

“They kept asking over and over again if I wanted medical assistance, and I kept saying, ‘No, I’m okay,’ ” Wolfe told The Washington Post late Thursday. “Once I got my wits to me and kind of calmed down, I realized that I was in fact not injured, and I was just in a really ironic situation.”

The saga, which Wolfe chronicled in a now-viral Twitter thread that has amassed hundreds of thousands of likes, began last week when she donned the blood-splattered costume to advertise a production of “Carrie: The Musical” put on by the Paramount Arts Center in Ashland, Ky. Ahead of the show’s Halloween opening night, a group of actors visited haunted houses in the state to promote the musical. But the person cast as Carrie couldn’t make it to a haunted house in rural Kentucky on Oct. 25, so Wolfe, who is playing the character of Sue Snell, stepped in.

When Wolfe left and headed home that night, she said she didn’t worry about her frightful look.

“We were in a haunted house campground in the middle of nowhere in Kentucky,” she told The Post. “I wasn’t in the position to be able to shower, and I thought nothing of it.”

Then, about 15 minutes into Wolfe’s drive back to Marshall’s Huntington, W.Va., campus, a deer bounded directly into the path of her car. At the time of impact, Wolfe said she was traveling around 55 mph.

Photos of her car after the accident show a white sedan with its hood badly dented and almost folded in half, exposing parts of the engine. The deer’s body was found in the road several yards behind the car, Wolfe said.

“Immediately after, I was in shock,” Wolfe said. “I saw a deer midair hit my car, so I was like, ‘Oh, my gosh, this is shocking.’ But then it hit me, ‘Holy crap, I’m head-to-toe dressed in blood makeup. They’re going to freak out.’ ”

She was right.

The motorist who stopped to check on Wolfe rushed to call for help when he saw her.

“I remember his face, and he looked horrified,” she said, noting that she had futilely tried to explain that it was only makeup and she was fine.

Wolfe said she also tried to warn the first responders when she called 911 herself. In a recording of the call published by Inside Edition, a person identified as Wolfe can be heard telling the dispatcher, “I’m in Halloween makeup, so I look like I have blood on me. It’s fake blood, so I don’t want ambulances to be freaking out.”

That didn’t stop “the whole squad” — three ambulances and two firetrucks — from descending on the scene, Wolfe said.

While the first responders were shocked and “taken aback” by the sight that greeted them, Wolfe said she was quickly able to set things straight.

“After I got the chance to explain that it was Carrie makeup, they thought it was hilarious,” she said. “They were absolutely wonderful. They couldn’t have handled it better.”

Police officers who arrived later were equally confused when they spotted Wolfe, bloodstains and all, chatting and joking with first responders.

“Are we going to ignore that this girl is gushing blood and needs medical assistance?” Wolfe recalled one of the officers asking.

On Monday, Wolfe, on the advice of a friend, decided to fire off a short tweet documenting the bizarre experience.

By the next morning, her tweet had received more than 200,000 likes — and they kept rolling in. As of early Friday, the tweet was approaching 400,000 likes and had just over 74,000 retweets. Wolfe said a recent check of her Twitter impressions indicated that at least 20 million people had seen the post.

“My senior superlative was most likely to be famous, and it’s just ironic that this is the way I got famous,” she said, laughing. “Everyone thought it would be like, ‘Oh, Broadway, singing,’ and now it’s, ‘Oh, she dressed up as Carrie and got into a wreck.’ ”

Wolfe added that social media users have now crowned her Miss Halloween 2019.

Some on Twitter were even inspired to share how their own costumes have also sparked unintended panic.

“I had my throat fake slit and people thought I was dead bc I fainted for a second,” one person tweeted.

Late Thursday, Wolfe said she originally planned to dress up as Daphne from “Scooby Doo” this year but decided to go as “viral Carrie.” As for future Halloweens, she said this one is going to be tough to beat.

“I’ll have to dress up as Stephen King characters and get in wrecks every Halloween to be able to keep up,” she said.