Tim Samaras, 55, his son, Paul Samaras, 24, and Carl Young, 45, died Friday while chasing a storm in El Reno, Okla., relatives told CNN Sunday.
"Thank you to everyone for the condolences. It truly is sad that we lost my great brother Tim and his great son, Paul," Jim Samaras wrote on his brother's Facebook page.
"Our hearts also go out to the Carl Young family as well as they are feeling the same feelings we are today. They all unfortunately passed away but doing what they loved," he added.
The men were stars of the former Discovery Channel reality show, "Storm Chasers."
"We are deeply saddened by the loss of Carl Young, Tim Samaras and his son. Our thoughts and prayers go out to their families," the network said in a statement.
Tim Samaras founded TWISTEX, the Tactical Weather Instrumented Sampling in Tornadoes Experiment, to help learn more about the development of tornadoes and increase lead time for warnings, the official website for the program said.