I4 timing belt

Is there a possibility of an engine failure from the timing belt letting go? Have the chance to pick up a 98 that this seems to have happened to and the garage is telling the person there is a "good" chance a piston whacked a valve..... FYI, engine wasn't running when this happened, must have went when they tried to start it the last time, and nothing.......

Thanks!

its a non interference engine.