The Los Angeles Chargers are placing tight ends David Njoku and Charlie Kolar on injured reserve, coach Jim Harbaugh announced Monday. Both will miss at least four games, leaving Oronde Gadsden as the only active tight end.

Njoku suffered a fibula injury in Sunday's 26-14 loss to the Las Vegas Raiders and was carted off. Kolar has a forearm injury. The Chargers may promote practice squad tight ends Evan Svoboda and Patrick Herbert.

The injuries severely impact an offense that relies on tight ends as blockers. General manager Joe Hortiz spent more on outside free agent tight ends than any other position. Kolar played 68 snaps and Njoku 40, compared to Gadsden's 34.

Harbaugh also said left guard Kayode Awosika (fibula) and defensive tackle Dalvin Tomlinson (hamstring) will miss time. Trey Pipkins III would start at left guard if healthy; otherwise Trevor Penning will. Five of the Chargers' eight free agent signings now miss games. The Chargers are 0-2 after upset losses to the Arizona Cardinals and Raiders.