The mechanic thinks the timing chain is broken. Could this cause more damage?

What is your question?

While driving down the interstate by check engine light came on followed by more lights and the traction control light. After I pulled off to the shoulder the engine died. After having it towed to the mechanic he thinks it's the timing chain but is worried it may have damaged the valves. Does anyone have experience with this? I thought with a timing chain the damage would be minimal to the engine?