(CNN) A Florida deputy came on the Hillsborough County Sheriff's Office main radio line early Wednesday to deliver a horrifying update.

Deputy Terry Strawn had harmed his family at one home. He harmed another family member at a different location. And he was going to kill himself.

A supervisor immediately joined the line to try and calm him down, and three other deputies located Strawn outside a high school in Plant City near Tampa, Sheriff Chad Chronister said Wednesday. Despite efforts to convince him otherwise, the deputy killed himself in front of his colleagues, the sheriff said.

The disturbing situation ended with the deaths of the deputy's wife, daughter and granddaughter, the deputy's suicide and the sheriff's call for police everywhere to take issues of mental health more seriously.

"We have to change the culture," Chronister said. "We have to make sure everyone knows that it's OK to ask for help. It's not a sign of weakness to say, 'Listen, I'm having a difficult time, I'm having a hard time, I need some help.' "

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