stupefied, astonished
Tom quedó estupefacto al oír que María había muerto.
Tom was stunned to hear that Maria had died.
Me quedé estupefacto.
I was stunned.
Me quedé estupefacto al escuchar lo que había pasado.
I was stunned to hear what had happened.
Yo estoy estupefacto.
I am stunned.