A mother and her young twin daughters were found dead in their Illinois home in what authorities are now calling a double murder-suicide.

Celisa Henning, 41, and her six-year-old twin daughters, Makalya and Addison, were found dead on Monday inside of their home in the 400 block of North Reed in Joliet, which is about an hour away from Chicago.

Police said that Henning was found with a self-inflicted gunshot wound to the head, with her daughters suffering from the the same fatal injuries.

Tragedy: Celia Henning, 41, and her six-year-old twin daughters, Makalya and Addison, were found dead on Monday inside of their home

Police are calling their deaths a double murder-suicide. Celisa Henning is pictured with her twins and husband

The six-year-old twins were found with fatal gunshot wounds to the head

Dennis Henning, the woman's father-in-law and the girls' grandfather told the Chicago Tribune that the girls stayed home with their mother on Monday.

He explained that his son, who is a plumber, tried contacting his wife during the day but she did not answer the phone.

When he arrived home around 3.30pm, he found the bodies of his wife and twin girls, Dennis said.

'He's grieving,' the Dennis said of his son. 'It's a tragedy... I hope and pray to God that he can live through it.'

Twins Makalya and Addison are pictured together on their fifth birthdays

The girls, pictured with their mother, had just started kindergarten at St. Paul the Apostle School

He shared that the girls had just started kindergarten at St. Paul the Apostle School and that his son was married to their mother for 10 years.

Joliet Police Chief Brian Benton did not reveal how the children or their mother died.

He did say they were found inside of a bathroom in the home.

Neighbor Joan Paul said she spoke regularly with the mother and described her as being devoted to her children.

The woman's husband and the children's father found them dead inside the home (above) on Monday afternoon after his wife did not respond to any of his calls or messages during the day

The girls had just started kindergarten at St. Paul the Apostle School. Authorities have not said if the mother left a note or revealed a motive for the tragedy

'If she did this, I can't imagine the terror in her heart,' Paul told the newspaper. 'Those kids were her life. She was an excellent mother.'

The Will County coroner will be conducting the autopsies.

Authorities have not said if the mother left a note or revealed a motive for the tragedy.