A total of four bodies have been found in the rubble of an early morning house fire in the exclusive Avila community north of Tampa, the Hillsborough County Sheriff's Office said.

Investigators said during a news conference on Wednesday around 5:30 p.m. that the house was set on fire intentionally.

Two adults and two teenagers were found dead in the home, and investigators have discovered two of the victims had upper body trauma.

Authorities said the house was being rented by Darrin Campbell, who lived with his wife and two children.

Although the identities of the victims have not been confirmed, officials say the Campbell's have not been accounted for and the children did not show up for their classes at Carrollwood Day School.

"The tenor of the school is sadness,” said Ryan Kelly, the head of Carrollwood Day School. “I think that is pervasive around the school as this unfolds further I think that will continue to be the tone of the school."

A neighbor called 911 and reported hearing an explosion from the home at 16223 Sierra de Avila around 5:45 a.m. Hillsborough County Fire Rescue crews found the 5,856-square-foot home on fire.

Crew found the fourth body just after 1 p.m. 

Students, family and friends of the family have been posting condolences on social media. Kelly said they've brought in additional grief counselors to help students cope with the tragedy.

"Obviously our hearts are broken at Carrollwood Day School," Kelly said. "We're grieving as a community and we've rallied around our students and our faculty and our parents."

Investigators working to determine cause of fire

Authorities said the fire destroyed a garage on the left side of the property burned in other areas for several hours after it started. Firefighters spent the morning battling the blaze from outside, and detectives were able to go inside, sheriff's spokeswoman Col. Donna Lusczynski said.

Hillsborough Fire Rescue officials said nearly half of the house burned.

The protracted blaze was "destroying potential evidence of what may have caused the fire and what may have led to the deaths of these individuals," Lusczynski said. "We’re going to be out here for days."

While fighting the fire and performing a cursory search of the residence, Hillsborough County Fire Department stated to detectives that they observed fireworks inside the residence.  It's not determined what kind of fireworks or where they were located.

The house is owned by retired tennis pro James Blake and is valued at $1.04 million, according to county property records. Blake leases the home out and confirmed through a spokesperson he was not there at the time of the fire.

Blake, 34, retired from competitive tennis last year after a 14-year career.