A Chicago pastor and his wife are in hospital fighting devastating injuries after being attacked while caring for one of their elderly mothers over the weekend.

Timothy and Renee Johnson were doing yard work at Renee's 95-year-old mother's Chicago home when the attack took place according to the Chicago Sun-Times.

Police have arrested a 28-year-old man who they allege carried out the attack after he offered to sell Timothy something and Timothy refused. While the man was attacking the pastor, Renee came out to help her husband and was subsequently attacked as well.

The newspaper describes a vicious attack, and the couple's daughter, Destinee, says in an online fundraiser that "They have suffered life-changing injuries that will impact them and our family forever."

She also says that Timothy has been battling Non-Hodgkins Lymphoma for a decade. The pastoral couple is also the caretakers for their elderly mothers.

“I really want you to understand, and I want the people to understand, how much of a giving person he is,” Renee says in an interview with CBSN Chicago. “He will give you the shirt off his back.”

“My parents’ hearts are so big. My parents’ love is overflowing,” she says. “We don’t know why this happened, right. But it’s a nightmare, but blessings in it as well.” She says it's a blessing because they've seen such an outpouring of support from others.

The 28-year-old man remains in custody and is undergoing a psychiatric evaluation.