Learn English – the verb for saying that you are suddenly frightened or afraid

single-word-requests

I am looking for a word that expresses that you are suddenly very afraid, frightened because of the actions of someone else. For example,

Mr. Smith had not expected his children to be inside his room, so when he entered the room and his children jumped on him he ______.

I'm not looking for something like became afraid or became frightened, because that expresses more long-term afraidness.

To be startled would work:

Mr. Smith had not expected his children to be inside his room, so when he entered the room and they jumped on him he was startled.

From Dictionary.com's entry on startle:

to disturb or agitate suddenly as by surprise or alarm.

to cause to start involuntarily, by or as by a sudden shock.

Or to jump. One can jump in surprise, see meaning 3 here:

to move or jerk suddenly, as from surprise or shock.

Although that wouldn't look too good in your example sentence since the word "jumped" already appears there. I would rephrase it as:

Mr. Smith had not expected his children to be inside his room, so when he entered the room and they sprang on him he jumped.