When Jessica and Derek Simmons first saw the beachgoers pausing to stare toward the water, the young couple just assumed someone had spotted a shark.

It was Saturday evening, after all, peak summer season in Panama City Beach for overheated Florida tourists to cross paths with curious marine life. Then they noticed flashing lights by the boardwalk, a police truck on the sand and nearly a dozen bobbing heads about 100 yards beyond the beach, crying desperately for help.

Six members of a single family — four adults and two young boys — and four other swimmers had been swept away by a powerful and deceptive riptide churning below the water’s surface.

“These people are not drowning today,” Jessica Simmons thought, she told the Panama City News Herald. “It’s not happening. We’re going to get them out.”

She was a strong swimmer and fearless in the face of adversity. But others had tried to reach them and each previous rescue attempt had only stranded more people.

There was no lifeguard on duty, and law enforcement on the scene had opted to wait for a rescue boat. People on the beach had no rescue equipment, only boogie boards, surf boards and their arms and legs.

“Form a human chain!” they started shouting.

Roberta Ursrey was among those caught in the treacherous riptide. From 100 yards away in the Gulf of Mexico, between crashing waves and gulps of salt water, she heard the shouting, she told The Washington Post.

By then, Ursrey and the other eight people stranded with her had already been in the water for nearly 20 minutes, fighting for their lives. Ursrey and the others had ventured into the water to rescue her two sons, Noah, 11, and Stephen, 8, who had gotten separated from their family while chasing waves on their boogie boards.

Tabatha Monroe and her wife, Brittany, in Panama City for a birthday getaway, were the first two to hear the boys’ panicked cries for help. The couple had just gone into the water when they saw the boys far from shore. They swam over and grabbed hold of their boogie boards.

But when they tried towing them back to shore, the women couldn’t break free of the current.

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They tried to swim straight and they tried to swim sideways, Tabatha Monroe told The Washington Post, but nothing worked. After about 10 minutes, a few young men with a surfboard snagged Brittany and towed her back to shore, just as the number of people who needed rescuing grew.

Soon Ursrey, who had heard her boys’ cries from the beach, was also caught in the riptide, followed in close succession by her 27-year-old nephew, 67-year-old mother and 31-year-old husband. Another unidentified couple struggled to tread water nearby.

“The tide knocked every bit of energy out of us,” Ursrey said.

So much water went up Tabatha Monroe’s nose that she was sure she would drown, she told The Post.

“I was exhausted,” she said.

On shore, the human chain began forming, first with just five volunteers, then 15, then dozens more as the rescue mission grew more desperate.

Jessica and Derek Simmons swam past the 80 or so human links, some who couldn’t swim, and headed straight for the Ursreys, using surf and boogie boards to aid their rescue efforts.

“I got to the end, and I know I’m a really good swimmer,” Jessica Simmons told the News Herald. “I practically lived in a pool. I knew I could get out there and get to them.”

She and her husband started with the children, passing Noah and Stephen back along the human chain, which passed them all the way to the beach.

By the time Jessica Simmons reached Ursrey, the 34-year-old mother could hardly keep her head above water.

“I’m going to die this way,” Ursrey thought to herself, she told The Post. “My family is going to die this way. I just can’t do it.”

Ursrey remembered Simmons coaxing her to carry on.

“I blacked out because I couldn’t do it anymore,” Ursrey said.

She woke up on the sand to the sound of more screams in the water.

Someone yelled that Ursrey’s mother, Barbara Franz, still in the water, was having a heart attack. Simmons told the News Herald that Franz’s eyes were rolling back. At one point, the 67-year-old woman told the rescuers “to just let her go” and save themselves. Instead, Ursrey’s husband and nephew held Franz’s body up as they struggled to keep their own heads above water.

“That’s when the chain got the biggest,” Ursrey said. “They linked up wrists, legs, arms. If they were there, they were helping.”

Nearly an hour after they first started struggling, just as the sun prepared to set, all 10 of the stranded swimmers were safely back on shore.

The entire beach began to applaud.

“It was beachgoers and the grace of God’s will,” Ursrey said. “That’s why we’re here today.”

Both Brittany Monroe and Franz were transported to a hospital. Monroe was later released after being treated for a panic attack and Franz remains hospitalized, her daughter said. She suffered a massive heart attack and an aortic aneurysm in her stomach, but has been taken off the ventilator and is considered to be in stable condition.

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The Ursreys plan to meet up with Jessica and Derek Simmons once Franz is released from the hospital, but Roberta said she could give hugs to the dozens of strangers who rescued her family.

“It actually showed me there are good people in this world,” Ursrey told The Post.

In a Facebook post, Jessica Simmons expressed a similar sentiment: “To see people from different races and genders come into action to help TOTAL strangers is absolutely amazing to see!! People who didn’t even know each other went HAND IN HAND IN A LINE, into the water to try and reach them. Pause and just IMAGINE that.”

The whole ordeal has given the Ursreys, who just moved to Florida from Georgia a month ago, a newfound respect for the power of the water.

“She’ll take you with her,” Ursrey said. “She almost took nine of us that day.”