New York History question - surrounding 9/11?

So I was watching the first season of the Sopranos, which aired in 1999. There is a scene where Tony’s mother was talking about New York, and how she hated the city. Here is the exact excerpt from the script:

Mom- I don’t like the people here.
Tony – You don’t know the people here.
Mom – And that city.
Grown men soiling themselves.
Tony – It’s not like that anymore, ma.
Mom – That giuliani.
Tony – Maybe we should just stick to the field trip.
Mom – Mothers throwin’ their babies out of skyscraper windows.
Tony – You’re always with the babies out the windows.

My question, and I don’t mean to be morbid… if this was 1999, that is before 9/11. What is she referring to?