SNELLVILLE, Ga. - Gwinnett County Fire investigators are still working to determine what caused a mobile home in Snellville to go up in flames early Saturday morning.The deadly blaze claimed the lives of a mother, Maria Isobel Martinez, and her three daughters, Ashley, Alexa and Daniela."That same night I left them and the last thing they told me was that they loved me," said Melvin Diaz, Martinez's husband and the father of the three girls.Diaz said he was devastated by the loss of his wife and little girls.Early Saturday morning, the mom and the 1, 3, and 5-year-old girls were inside their Snellville home off Smokecreek Parkway.