A California sheriff's deputy is donating one of her kidneys to the 3-year-old son of a former co-worker, KTTV reported.

Riverside Deputy Alicia Lopez will be the donor for Matthew Castleberry, whose mother, Angelina, worked with her in Palm Desert.

Angelina Castleberry gave birth to twins, but Matthew was diagnosed with posterior urethral valves and was born with pulmonary hypertension, bleeding and fluid in his brain, kidney failure and collapsed lungs, KTTV reported. The boy has undergone 14 surgeries and is currently on dialysis. He has had three failed donor matches, KTTV reported.

But Lopez was a match, to the surprise of the Castleberry family.

"I called [Angelina] and asked her if she was sitting down," Lopez told KESQ.  "I didn't realize how rare this was until she explained it to me over the phone and I just stood there with my mouth open for a minute."

The surgery is set for later this month.

"When you see [Matthew’s] face, it's kind of hard to say no," Lopez said.