You're using information given to us from the Hamasastan, known for it's free press and accuracy? I believe they said the man was 911 and his grandson was 333. Please don't forgot the final digit when reporting the ages of the victims.
Justice Ministry: Information examined by AG about Gal Hirsch didn't come from police (Haaretz)
from the article: Reports: IDF shelling kills 3 Palestinians near Gaza border