The San Francisco 49ers have lost two players for the season during an organized team activity on Monday.

Offensive lineman Justin Skule suffered a torn anterior cruciate ligament in his knee, and safety Tarvarius Moore tore his Achilles.

While neither Skule nor Moore has been an established starter for the Niners, both have played prominent roles in recent seasons.

Skule has played in 31 regular-season games over the past two years with 12 starts at tackle and guard.