Ronnie Hillman – Super Bowl champion running back with the Denver Broncos – dead at 31

Ronnie Hillman – who played for the Denver Broncos when they won the Super Bowl in February 2016 – has died at age 31.

Hillman's family announced his death on Instagram.

"It is with heavy hearts that we announce the passing of our beloved son, brother & father, Ronnie K Hillman Jr.," the post read. "Ronnie quietly and peacefully transitioned today in the company of his family and close friends."

The Instagram post added, "We as the family, appreciate the prayers and kind words that have already been expressed."

Hillman entered hospice care on Tuesday. The former NFL player died after a battle with a rare and aggressive cancer, according to the family.

"Though this message is difficult to share, we feel it is necessary," the family said in an Instagram post shared on Wednesday. "August of this year, Ronnie was diagnosed with Renal Medullary Carcinoma. Renal Medullary Carcinoma (RMC) is a rare but highly aggressive neoplasm form of cancer that primarily affects young African Americans with sickle cell trait. Unfortunately treatment has not been successful and our beloved RJ is currently under Hospice Care where he is being kept comfortable and out of pain."

The National Organization for Rare Disorders (NORD) defines renal medullary carcinoma as a "rare cancer of the kidney that predominantly afflicts young people of African descent who carry the sickle cell trait, sickle cell disease, or other sickle hemoglobinopathies that can cause sickling of the red blood cells."

The exact cause of renal medullary carcinoma is not fully understood, according to the National Organization for Rare Disorders.

Hillman was a running back at San Diego State, where he is fifth on the school's all-time rushing list.

At age 20, Hillman was drafted in the third round by the Denver Broncos in 2012.

During the 2015 NFL season, Hillman led the Broncos in rushing with 863 yards and scored a team-high seven touchdowns.

Hillman was a running back on the Broncos team that won Super Bowl 50 with Peyton Manning as Denver's quarterback.

Hillman also played for the Minnesota Vikings and San Diego Chargers. In 2017, Hillman was signed by the Dallas Cowboys but was let go before the start of the season. Hillman's NFL career ended after he was released by the Cowboys.