Dameon Burcie, who is a lieutenant in the Dallas Fire Department, said his son Dyrk died peacefully on Monday at the family home in Dallas.
Dyrk was "one of the happiest kids you could ever find," Dameon Burcie said.
Dyrk Burcie was 3 when his parents noticed a mass on his abdomen while he was taking a bath. Doctors diagnosed him with pediatric liver cancer and later found the cancer had spread to both of his lungs.
Dyrk underwent nine rounds of chemotherapy and a liver transplant. "The last few weeks, he had some discomfort with all of his surgeries and chemotherapy," his father said.
In April, Burcie posted on Facebook that the family had decided to stop intensive treatment and make the most of the time Dyrk had left. Family friend and fellow Dallas firefighter Ronnie Roe talked to other firefighters about sending Dyrk photos of them posing with signs emblazoned with the boy's name.
The Dallas firefighters' photo project caught on with crews at other fire departments, who also posted images on a Facebook page devoted to Dyrk.
In one photo, firefighters from Longview, in East Texas, spelled Dyrk's name in hay before dousing it in oil and liquid detergent and setting it on fire. A firefighter snapped a photo of the boy's name in flames from up on a nearly 100-foot-tall ladder.
In College Station, about 90 miles northwest of Houston, firefighters posed in front of two trucks with their cabs tilted forward. Two logos from the "Transformers" action figures - Dyrk's favorite - were digitally added.
Fire crews from throughout the country posted photos of support for Dyrk, as did many non-firefighters, including other children his age, youth sports teams, beauty queens and active-duty soldiers.
"It was absolutely incredible," Burcie said of the response. "Dyrk would ask almost every day if he could see the pictures that had been posted that day."
The boy's funeral is scheduled for Friday at First Baptist Church of Midlothian. He will be buried at Mount Zion Cemetery near Midlothian, 30 miles southwest of Dallas.
"Our thoughts and prayers are with the Burcie family," Dallas Fire-Rescue spokesman Jason Evans said in an email. "Dyrk's resilience, and smile, has taught us all a lesson in how to approach every day of our lives; and for that he will forever be in our hearts."