MINNEAPOLIS - A young Minnesota boy is fighting for his life after contracting a toxin producing bacteria -- one that killed his sister on Sunday.

Tyffani Maresh said her two children Kade and Kallan became very ill earlier this month from a "bad shiga toxin producing bacteria," requiring several visits to the ER before they were rushed to the University of Minnesota Masonic Children's Hospital, according to their CaringBridge page.

She said both had acute kidney failure and in Kallan's case, the toxins also damaged her neurological system. According to the journal posts, a week after becoming sick, Kallan passed away Sunday night.

"We were able to give Kallan a bath and put her favorite jammies on her," Tyffani wrote. "We got to hold her free of tubes and snuggle and kiss her. She is the most amazing little girl in the world. Our hearts are aching with the deepest sadness."

While the family mourns their sweet girl, their young son is still fighting.

Maresh states the toxins have reached both of Kade's kidneys but not his neurological system. He's had blood transfusions, kidney dialysis and a platelet transfusion as doctors work to get his blood work back to normal.

"Please pray for my baby boy to stay strong and keep fighting," Tyffani wrote. "It is absolutely heartbreaking watching your babies in so much pain and being so helpless."

A gofundme page has been created to help the family with medical expenses. The fundraiser had a goal of $20,000 but has more than doubled that amount in one day. At last check on Tuesday afternoon, more than $42,600 had been raised.