SANTA CLARA, Calif. -- Through the first four practices of this training camp, most of the injuries suffered by key San Francisco 49ers had been at the safety position. That changed Wednesday when defensive tackle DeForest Buckner suffered an apparent left ankle injury about midway through the session.

Buckner, who is expected to be a big piece in coordinator Robert Saleh's defense, didn't appear to be banged up too badly, though, as he was able to put weight on the ankle and spent time stretching it out with head athletic trainer Jeff Ferguson. Buckner had the ankle taped up, but the Niners clearly didn't want to risk further injury and he sat the rest of the practice.

With Buckner out, the Niners turned to Chris Jones and rookie Solomon Thomas to take the reps with the first-team defense at the 3-technique defensive tackle spot. Jones later looked to suffer an arm injury of some sort but did not come out. Thomas got his work mostly in nickel packages as he continues to work as the "big" defensive end on normal downs.

DeForest Buckner was forced to leave Wednesday's practice after suffering an ankle injury, but the veteran defensive lineman was able to put weight on the ankle. Stan Szeto/USA TODAY Sports

Some other news, notes and observations from Wednesday's practice:

The Niners will be back at practice on Thursday morning.