Adam Schefter breaks down Todd Gurley's 4-year contract extension worth $60 million, with a record $45 million in guaranteed money, resetting the market for running backs. (1:36)

The Los Angeles Rams and Todd Gurley have agreed to a four-year contract extension that, according to ESPN's Adam Schefter, resets the market for running backs.

The Rams announced Tuesday that the extension keeps Gurley under contract through 2023 but did not disclose financial terms. A source told Schefter that the deal is worth $60 million and includes $45 million guaranteed, the largest guarantee given to a running back.

Gurley also will receive a $20 million signing bonus, the source told Schefter. It is the largest per-year average for any running back, providing a new benchmark for other running backs looking for new deals, such as Arizona's David Johnson and Dallas' Ezekiel Elliott.

The deal was noticed by Steelers star running back Le'Veon Bell, who has been unable to agree to a long-term contract with Pittsburgh and has received a franchise tag in back-to-back years.

Bell, who will make $14.5 million this season with his franchise tender, congratulated Gurley on Twitter and added a reference to his own demands in a second tweet.

lol and ppl thought I was trippin?... — Le'Veon Bell (@LeVeonBell) July 24, 2018

Gurley, 23, already had been under contract with the Rams through 2019, when he is scheduled to make $9.63 million under the fifth-year option on his rookie contract.

Gurley's deal comes a week after the Rams signed wide receiver Brandin Cooks to a five-year, $80 million extension. Rams general manager Les Snead was asked Tuesday about what the deals mean for the negotiations with star defensive tackle Aaron Donald, who sat out training camp last year and offseason activities this year over his contract.

"Each situation is different. Different players, different agents," Snead told reporters. "You work on everything simultaneously, but you really don't know when you're going to get something done or not because it's case by case."

Snead said that negotiations to extend Gurley began in the spring, "to get ahead of the curve" with the fourth-year player.

"He's a big weapon for us," Snead said Tuesday.

"Last year's production isn't really a reflection of the value that he provides because he did such a great job, but he's so much more than that to our team," Rams coach Sean McVay said. "The way that he competes in protection, the way that he works and the way that rubs off on his teammates."

After being selected with the 10th overall pick in the 2015 draft, Gurley was named the NFL's Rookie of the Year in 2015 after rushing for 1,106 yards and 10 touchdowns.

But he struggled in his second season after the Rams' relocation to Los Angeles, failing to rush for more than 100 yards in a single game and finishing with 885 rushing yards and six touchdowns as the team stumbled to a 4-12 record under coach Jeff Fisher, who was fired.

Gurley completed a major bounce-back last season playing in McVay's explosive system, rushing for 1,305 yards and 13 touchdowns while catching 64 passes for 788 yards and six more TDs. The former Georgia star won the league's Offensive Player of the Year award in 2017.

ESPN's Lindsey Thiry contributed to this report.