Earl Thomas has become the NFL's first $10 million-a-year safety.

Thomas and the Seattle Seahawks agreed to a four-year contract extension, the team said Tuesday. Although terms were not disclosed, sources confirmed Monday to ESPN that the deal is worth $40 million and makes him the league's highest-paid safety in terms of average salary.

The deal includes $27.75 million in guaranteed money, sources confirmed to ESPN.

"This is a family to me," Thomas said at a news conference to discuss his extension. "I love everybody in this organization. It's not about me. It's about the people that helped me along the way, too. This is where I grew up [as a football player]. I'm excited to keep this going."

Thomas received praise from Pro Bowl cornerback Richard Sherman.

Thomas, 24, recently completed his fourth season with the Seahawks and was named to the Pro Bowl for the third consecutive year.

He is widely regarded as the best safety in the league, and now his salary will reflect it.

Former Buffalo safety Jairus Byrd signed a six-year, $54 million contract with New Orleans last month that made him a $9 million-per-year safety. The deal included $28 million in guaranteed money.

Prior to Monday's deal, Pittsburgh's Troy Polamalu had the highest average salary of any safety at $9.867 million.

Thomas, who will make $4.625 million in base salary in the final year of his rookie contract, recorded 105 tackles and five interceptions last season and was one of the top defensive players during Seattle's run to the first Super Bowl championship in franchise history.

ESPN NFL Insider Adam Caplan and ESPN.com Seahawks reporter Terry Blount contributed to this report.