The fifth body found at the home of Don and Sandra Pyle wasn't immediately identified by the Anne Arundel County Fire Department. The Pyle's 16,000-square-foot home caught fire Monday morning and quickly spread throughout the structure.
The couple had four of their grandchildren - Alexis (Lexi) Boone, 8; Kaitlyn (Katie) Boone, 7; Charlotte Boone, 8; and, Wesley (Wes) Boone, 6 - at their home at the time, according to relatives. All six are believed to have died in the four-alarm fire, though it's unclear what caused the blaze.
In a statement released Thursday, members of the Boone and Pyle families thanked those who have offered them comfort but added, "Our loss demands time and quiet reflection to process these feelings. We ask that you respect our need for privacy.
"Life is fragile," their statement read. "Make time today to embrace your loved ones."
Don and Sandra Pyle had spend the night before the blaze treating the children to a special night at the Medieval Times restaurant, according to a family spokeswoman. The couple also took the children to Target so they could get costumes before going to the restaurant.
The fire is being handled as a criminal investigation, said officials. The U.S. Department of Alcohol, Tobacco, Firearms and Explosives also sent investigators.
ABC News' Emily Shapiro, Bazi Kanani, Dan Good and The Associated Press contributed to this report.