A struggling children's author killed his wife and their three young children in a murder-suicide, police have ruled.

Joseph Zaccardi, 43, and his family were found dead in an Abington, Massachusetts, condominium complex at about 7.30am on Monday by a relative who showed up to take the children to school.

Plymouth District Attorney Timothy J. Cruz's office said Wednesday Deirdre, 40, and her three children - Alexis, 11, and 9-year-old twins, Nathaniel and Kathryn - died from 'shooting by firearm and the manner of the deaths were determined to be homicide'.

The medical examiner ruled Joseph 43, died from 'a gunshot wound and the manner was suicide', The Boston Globe reports.

Plymouth District Attorney Timothy J. Cruz’s office said: 'The investigation is ongoing by State Police Detectives assigned to the Plymouth County District Attorney’s Office and Abington Police. No further information is available.'

Abington police Chief David Majenski had said there was no history of domestic issues with the family.

But Joseph described himself as 'unemployed and going crazy' on his Facebook page, where he also sold copies of his books including 'What Kind Of Dragon Would You Be?'

Scroll down for video

Alexis, 11, and 9-year-old twins, Nathaniel and Kathryn died from 'shooting by firearm and the manner of the deaths were determined to be homicide'. Police say they were killed by their dad

Police were said to have found Deidre's body first before finding their children and father

Joseph described himself as 'unemployed and going crazy' on is Facebook page, where he also sold copies of his books including 'What Kind Of Dragon Would You Be?'

A relative called 911 after Deidre was found unresponsive and bleeding on a couch, according to The Patriot Ledger.

Police were said to have found Deidre's body first, in the downstairs area of the home, before finding the bodies of the three children and their father. The locations of the other bodies were not revealed.

There were no other people in the condo unit.

'It's a crime, a crime occurred in that building. Three little children are gone forever,' said Cruz.

Deirdre was a long-time employee and office manager at EMI Strategic Marketing, according to a statement issued by company president Campbell Edlund, obtained by the Boston Globe.

Edlund wrote that 'Deirdre was a lovely person—a trusted employee and valued friend to all of us at EMI,' who had worked with the company for almost 20 years.

She was said to have taken the previous Wednesday off to celebrate the twins' birthday.

Joseph Zaccardi, 43, and his family were found dead in an Abington, Massachusetts, condominium complex at about 7.30am on Monday. The medical examiner ruled Joseph 43, died from 'a gunshot wound and the manner was suicide'

A woman from the Massachusetts Chief Medical Examiners Office, center, uses a gurney at the home where the two adults and three children were found dead with gunshot wounds

All three children attended Abington Public Schools, Superintendent Peter Schafer said in a message to parents that was shared with the media.

He called the deaths an 'unexpected and unexplainably tragic loss.'

'This morning we were informed of the unexpected and unexplainably tragic loss of the Zaccardi family,' Schafer wrote.

'Their presence touched so many lives and there are no words to express the sadness we feel.

Counselors have been made available to students, he said.

The victims' relatives put out a statement through the Plymouth District Attorney's Office.

'Today our family has suffered an unfathomable loss,' they said in the statement. 'As we attempt to make sense of the enormity of this event, we respectfully ask that the media respect our family's wishes to be left alone as we grieve our tremendous losses in private.'

Abington, a town of about 16,000 people, is about 20 miles south of Boston.

Sarah Gregonis Wall said of her friend Deirdre: 'If you needed something, she wouldn’t even bat an eyelash. She would be there in a heartbeat.'