The former child star's manager Dino May confirmed the sad news to The Hollywood Reporter.
A source said that Sawyer "was visiting family in Texas. He went on the front porch and killed himself with a gunshot to his head."
The source added, "Sawyer's entire family is absolutely devastated by this tragedy."
Sawyer's sister Madylin Sweeten, who played Ray's other child Ally Barone on "Everybody Loves Raymond", posted on Facebook, "At this time I would like to encourage everyone to reach out to the ones you love. Let them have no doubt of what they mean to you."
Sawyer and Sullivan joined the show when they were 16-month-old in 1996. They jointly played a character in a 2000 episode of Disney's "Even Steven" and shared a small role in 2002's "Frank McKlusky, CI".