About the usage of 'surprised'
They were very sad/surprised (which is proper to use here) to hear that their son had been hit by a car.

Can 'surprised' be used to describe someone's emotions this way(in this context)?I mean It's like saying you are surprised at your own son's death!!! And this is correct expression?

Question

About the usage of 'surprised'
They were very sad/surprised (which is proper to use here) to hear that their son had  been hit by a car.

Can 'surprised' be used to describe someone's emotions this way(in this context)?I mean It's like saying you are surprised at your own son's death!!! And this is correct expression?

Answer

Both are technically correct! They could be both sad and surprised to hear their son had been hit by a car... The surprise in this context may refer more to the unexpectedness.

Answer

"Surprised" is not a good adjective to use in these circumstances at all!  It would mark you out as a complete foreign learner.  We would normally say "They were deeply shocked and saddened to learn that their son had died in a car accident."