NEW YORK -- Former 13-year NBA veteran forward Anthony Mason is "literally fighting for his life" because of a serious heart ailment, a source close to Mason confirmed to ESPN.com.

Mason suffered a heart attack several days ago and has since had multiple surgeries at a New York hospital, the source said.

"We're just hoping for the best at this point," the source added.

The New York Knicks, one of the six teams Mason played for, tweeted out a message of support for the 48-year-old on Wednesday evening.

Our thoughts and prayers are with Anthony Mason and his family. #Knicks — NBA New York Knicks (@nyknicks) February 11, 2015

Longtime New York-based NBA writer Peter Vecsey first reported details of Mason's condition.

Some of Mason's former teammates were bracing for the worst on Wednesday night, sources told ESPN.com.

Ex-Knick Mark Jackson tweeted his support for Mason.

Praying for my former teammate Anthony Mason!!! — Mark Jackson (@MarkJackson13) February 12, 2015

Mason played in the CBA and USBL in addition to his years in the NBA. The 6-foot-7 forward was perhaps best known for his five seasons with the Knicks.

Mason teamed with Charles Oakley, Patrick Ewing and John Starks to help lead the Knicks to the NBA Finals in 1994. He won the NBA's Sixth Man Award in 1994-95 while playing for Pat Riley. His rugged play epitomized the nature of Riley's Knicks teams.

Later in his career, Mason was reunited with Riley while playing for the Miami Heat. He was named to his one and only All-Star team in 2001 with the Heat and finished his career with the Milwaukee Bucks.

ESPN.com's Ramona Shelburne and Ohm Youngmisuk contributed to this story.