This story originally appeared on People.com.
Twin sisters out for a morning stroll during their family vacation in Mexico drowned when a rogue wave swept onto the beach and dragged them into the Pacific Ocean.
The 67-year-old women, Barbara Thomas of McKinney, Texas, and Beverly Skripsky of Scottsdale, Arizona, died Oct. 22 while walking on the beach near the house they were renting in Cabo San Lucas, Mexico. The twins often traveled together and were on the third day of their week-long vacation.
“We are all still in shock from this unbelievable tragedy,” Skripsky’s son, Matt Skripsky, tells PEOPLE. “Dangerous waves ended the lives of two wonderful women.”
Other tourists to both Cabo San Lucas and San Jose del Cabo have also been pulled into the water and drowned, prompting a warning from the U.S. Embassy and Consulates in Mexico about strong currents, riptides and large waves.
“Swimmers, waders and even people simply walking along the beaches have been washed into the ocean by rogue waves,” according to the embassy.”Some have drowned and others have disappeared.”
Potentially dangerous waters are not always evident. “Not all hazardous beaches in this area are clearly marked,” the embassy says. “Strong currents could lead to dangerous conditions for even the most experienced swimmers.”
Barbara Thomas’s husband, Steve Thomas, said the massive wave overwhelmed the women in an instant.
“I can’t imagine how fast it was moving but it went from 10 feet to 15 feet in seconds,” Thomas told Chicago TV station NBC-5. “They found two women out at sea and I’m thinking, ‘Great, they found them’ and I say, ‘Are they okay?’ and he says, ‘I’m sorry to tell you sir, but they’re deceased.'”
The twins, both retired, were active, warm and wonderful wives and mothers who enjoyed spending time with their grandchildren, Skripsky says. They traveled the world together, and had recently returned from a trip to Dubai.
His mother, Beverly Skripsky, had worked as a travel agent and later as a resort concierge. “People were drawn to her upbeat and fun personality,” he says. “She made friends everywhere she went.”
His aunt, Barbara Thomas, had worked as a director at an assisted living facility and volunteered at Head Start and Meals on Wheels.
She “found great joy in helping others,” he says.