FLEMING ISLAND, Fla. -- A Clay County woman called 911 early Tuesday morning to report finding her husband and two children dead in what investigators believe was a double slaying and suicide.

Clay County Sheriff's Office Sgt. Dan Mahla said it appears that 49-year-old Jerry Whitelaw shot his 16-year-old son, Kevin, and 11-year-old daughter, Katie, inside their home on Grande Oaks Way in the Margaret's Walk subdivision just after 6 a.m. before turning the gun on himself.

Mahla said they believe the two children were killed in their sleep, then Whitelaw shot himself while his wife was in the shower.

"It has the appearance of being a murder-suicide," Mahla said. "Anytime it's involving children, it's devastating."

Grief counselors were available at the two children's schools: St. Johns Country Day and Grace Episcopal Day School. Dana Whitelaw also works as a secretary at Grace Episcopal.

"Our prayers are with the entire family," said the Rev. Kurt Dunkle of Grace Episcopal. "In times like this, it is only God that you can rely on and who will be there to pick up the pieces."

Greg Foster, the headmaster of St. Johns Country Day, where Kevin was a student and played on the football team, said the school announced what happened before class Tuesday.

"Our students and our teachers care very deeply about each other," Foster said. "The kids and the adults know each other, care about each other a lot. The terrible news this morning has left our school with a profound sense of loss."

William McGauley, the father of Dana Whitelaw, issued this statement on behalf of the family Tuesday afternoon:

“On behalf of my daughter, Dana, I would like to thank the families of Grace Episcopal Day School, Grace Episcopal Church, and St. Johns Country Day School for their incredible outpouring of love, support, and prayers for my family. I cannot tell you how much it means to my daughter and the rest of my family to know how much we are loved.
"There are no words to describe this loss. The enormity of this tragedy cannot be absorbed in such a short period of time. The grief we feel is overwhelming, and so we ask for and appreciate your patience as we make the necessary arrangements to lay our family members to rest.”

Court records show Dana Whitelaw had filed for divorce in August. While the sheriff's office had no record of previous police calls to the home, Mahla said, "There were some domestic issues."

A neighbor told Channel 4's Dan Leveton that she saw Jerry Whitelaw and the kids outside Monday night and everything appeared to be fine. She told Channel 4's Jim Piggott she had not heard the couple was getting a divorce until after the shootings.

"It's crazy," neighbor Ashley Gann said. "I was in total shock."

Deputies continued to gather evidence at the home in the gated community off U.S. Highway 17 just north of Green Cove Springs.

The community held a prayer candlelight vigil for Kevin and Katie Whitelaw Tuesday night at Grace Episcopal Church in the wake of the tragedy. About 700 people gathered at the church in Orange Park, which had standing room only.

"Our hearts go out to them and our prayers," said a friend of the family who attended the vigil. "We just love Dana, and God bless Kevin and Katie."

This case joins the ongoing investigation into the disappearance and slaying of 7-year-old Somer Thompson, a recent double slaying at a Fleming Island nightclub and other high-profile crimes. The sheriff's office of this bedroom community of Jacksonville admits it is being stretched.

"I think our whole agency is maxed to the limit right now," Mahla said. "Thank goodness that we've had the Federal Bureau of Investigation, the Florida Department of Law Enforcement, the United States Marshals, NCIS and a lot of our neighboring agencies have come down to help us at this time."