A sheriff's deputy in Florida horrifically killed his wife, daughter and granddaughter, before shooting himself dead in front of his fellow deputies outside of a high school.

Hillsborough County Sheriff's deputy, 58-year-old Terry Strawn, killed his wife Theresa, 54, and his 6-year-old granddaughter Londyn at their home, before killing his 32-year-old daughter Courtney at her home, according to the Tampa Bay Times. Terry then shot himself dead in front of Plant City High School.

His cousin Jimmy Strawn, posted to Facebook about the awful tragedy, 'This morning my cousin, Deputy Terry Strawn, killed his wife, daughter, and granddaughter, then killed himself. We are truly devastated and are still trying to wrap our heads around it.'

'Please,' his cousin urged, 'if you are considering suicide, REACH OUT!! We would have done ANYTHING for Terry, Theresa, Courtney, and little Londyn. We miss you and love you all.'

Hillsborough County Sheriff's deputy Terry Strawn, 58, right, killed his wife, Theresa, 54 (left) his 6-year-old granddaughter Londyn (pictured) at their home, before killing his 32-year-old daughter Courtney (in green) at her home

Terry started with the Hillsborough County Sheriff's office in 1991, and had briefly retired and returned to the force after retiring two-years-ago (right, Courtney with her daughter in 2014)

The Hillsborough County Sheriff's office is seen investigating one of the homes where the victims were killed in Dover, Florida

The incident unfolded before 7am Wednesday morning. Deputy Strawn went onto the main sheriff's radio channel to say 'he had caused harm to his family.'

'Then he advised was going to kill himself at Plant City High School,' Hillsborough County Sheriff Chad Chronister said during a press conference Wednesday.

'A supervisor got on the air to try to calm him down, to ensure him it's a temporary problem.'

The deputy mentioned financial and health issues on the radio, Chronsiter said, but he had no more details.

While he was on the radio, three deputies went to the high school and spotted him just off the school property.

A Hillsborough County Sheriff Forensics Deputy enters a home where a deputy killed his relatives in the area of Dover, Florida before killing himself near a high school in Plant City

The Hillsborough County Sheriff Chad Chronister and his staff investigates a deputy killed who three relatives at their homes in Dover, then killed himself near Plant City High School

A Hillsborough County Sheriff Office Forensics vehicle enters a subdivision where a deputy killed three of his relatives at their homes in Dover

Hillsborough County Sheriff Chad Chronister enters a community where the deputy killed his family members

Hillsborough County Sheriff Chad Chronister (picutred) declined to identify the sheriff's deputy or the two women and child he killed Wednesday morning in Plant City, Florida

Sheriff Chronister held a press conference on Wednesday following the incident

The sheriff's department made sure to let the community know the incident was not related to the school while urging motorists to stay out of the area

They made every attempt to stop him from killing himself, but they were unable, according to Chronister.

At Plant City High, staff was trying to keep people away from the scene of the Sheriff's Office investigation on the northeast area of the campus, the Tampa Bay Times reports.

There were reports of shots fired just before 7am but students and staff were not involved.

The school was not placed on lockdown.

The rural town of Plant City was rocked by the news that a sheriff's deputy had killed two women and a baby at two different homes before going to Plant City High School and shooting himself dead in front of three other deputies

The deputy had been with the Hillsborough County Sheriff's office since 1991. There was 'no indication whatsoever that would lead us to believe' that the deputy would do something like this, Chronister said, according to ABC Action News.

He had retired two years ago but was brought back on to do security at a local elementary school following the Parkland school shooting.

The Hillsborough County Sheriff's Office made the decision to hire him back permanently, and according to Chronister the deputy was so happy to be hired back as a full time deputy sheriff.

Names of the victims and the deputy weren't immediately released.

This is the second time a Hillsborough County Sheriff’s deputy was involved in a murder-suicide. On Sept. 24, a deputy killed his wife and then himself while the couple’s four children were home.