A sheriff's deputy in Florida shot and killed his wife, daughter and granddaughter before killing himself, authorities said.

Hillsborough County Sheriff Chad Chronister identified the victims at a news conference Wednesday as Theresa Strawn, 54, Courtney Strawn, 32, and 6-year-old Londyn Strawn. They were found dead at two different homes in Plant City.

The sheriff's deputy, 58-year-old Terry Strawn, took his own life near Plant City High School.

Just before 7 a.m. ET, deputy Strawn was heard on the department's main radio channel saying that he had "caused harm" to his family and gave the address to two different homes, Chronister said. The sheriff's deputy then said that he was going to the high school to kill himself, Chronister said.

Hillsbourough County Sheriff Chad Chronister briefs the media on a deputy involved in a murder-suicide. Hillsbourough County Sheriff

"The supervisor immediately got on air and did everything that they could to try and calm him down," he said.

Strawn was confronted near the school's property by three other deputies, who tried unsuccessfully to stop their colleague.

Theresa Strawn and her granddaughter, Londyn, were found dead at one home and Courtney, Londyn's mother, was discovered dead at the second home. Chronister said he's not sure why the sheriff's deputy went to the high school, but believes it was because it was close to one of the homes.

Deputy Strawn, who had been with the department since 1991 and was hired back over the summer after retiring to work as a school resource officer at an elementary school, mentioned over the radio that he was having financial and health problems.

Chronister said a background check the department conducted before rehiring the deputy did not show any financial troubles.

"I'm saddened, but I'm also disheartened that a deputy sheriff would ever cause harm to another individual," Chronister said.

This is the second murder-suicide to hit the sheriff's department in recent months. In September, Hillsborough County Deputy Kirk Keithley committed suicide after murdering his wife while their four children were at the home, NBC-affiliate WPTV reported.

Chronister briefly mentioned the September incident during the press conference, urging people to seek assistance if they may need it.

"It's OK to ask for help," he said. "It's not a sign of weakness."

If you or a loved one are looking for help, please call the National Suicide Prevention hotline at 1-800-273-8255.