Investigators are trying to piece together the deaths of a family found shot inside a burned-out Florida mansion owned by tennis star James Blake.
All four of the people had been shot, authorities said, and detectives recovered a gun registered to Darrin Campbell, a career executive who lived in the house with his wife and two teenage children.
WATCH: 4 Killed in Fire at Ex-Tennis Player's Home
Authorities say they aren't seeking suspects, but the situation has not been classified a murder-suicide.
"We're not leaving any stone unturned on this case," said Hillsborough County Sheriff's Office Col. Donna Lusczynski.
Surveillance video obtained by ABC News shows Campbell, who lived in the home with his wife, Kim, and two children - purchasing $650 worth of fireworks from a shop in Tampa Bay three days before the fire.
William Weimer, vice president of Phantom Fireworks, said Campbell's actions didn't raise any eyebrows.
"The type of products he purchased and the amount he spent was pretty typical," Weimer said.
Fireworks were found throughout the mansion. Campbell also purchased several cans of gasoline, authorities said.
Authorities still have not positively identified the bodies found inside as those of the Campbells, but police said they had been renting the property from a former tennis star, and the family has not been accounted for. A relative said they were inside the home at the time of the fire.
Blake has been renting the home to Campbell and his wife Kim for the past two years. Their children, Colin, 19, a high school baseball standout, and Megan, 16, a dancer, also lived in the home.
The situation has left Kim Campbell's father, Gordon Lambie, in complete shock.
"I just lost one of my two children and my grandchildren," he said, "and I don't understand how this happened."
The Associated Press contributed to this report.
Dad Bought Fireworks, Gas Before Fire at Tennis Star's Home