Timing belt snapped is it possible valves are damaged?

My timing belt snapped, is it possible on this model car for the valves to be damaged?

Car model: Honda Ballade/Civic 150. 1985 yearmodel. Automatic.

the timing belt snapped while I was driving at approx. 40km/h. How big are the odds of damage to the valves? How do I know if the valves are damaged, if they are damaged?

I'm no expert on cars and need this information so I won't be done in by the mechanic fixing the timing belt.