THORNTON, Colo. Four members of a Colorado family were killed and another person seriously injured in a fiery two-vehicle crash in Thornton Saturday night.The crash occurred around 7:30 p.m. at the intersection of Thornton Parkway and Washington Street, according to the Thornton Police Department.Police said one of the two vehicles involved in the crash caught fire, killing all four occupants inside. The driver of the second vehicle was transported to the hospital with serious injuries. The victims' family members identified the four people killed in the fiery crash as follows:Francisco Daz - father.Beatriz Nez - mother.Paola Daz - 15-year-old daughter.Nataly Daz - 10-year-old daughterDaniel Daz, a family member, told Denver7 that the four were leaving church and heading to Walmart at the time of the crash.He said the trauma is so fresh that he has not fully registered it yet."We feel lost. We don't even know what's the next step, Daz said. "It doesn't even seem real yet because it's hard to believe. Daz said he first learned about the crash from an alert on his phone.I get a message, the notification on my phone saying that my little sister was detected in a crash," he said. "That's when I ran out. I went to my car. I called my brother.The cause of the crash is under investigation. Police did not release additional details. 'We feel lost': 4 members of Colorado family killed after fiery two-vehicle crash in Thornton