The 10-month-old boy miraculously survived and was in critical but stable condition at a Harlem hospital Thursday, police said.
A New York police spokesman confirmed that the woman left behind a suicide note.
Bystanders were shocked when they saw the 45-year-old mother fall Wednesday afternoon.
“I wish I never witnessed that,” Steven Dominguez told CNN affiliate WPIX. “It’s disturbing, and horrible. The baby bounced off her chest onto the floor, face down and was crying. My mother tried to pick up the baby, but there was already a detective there.”
Earlier, neighbor said he heard yelling coming from the woman’s apartment before she fell.
The woman was arguing with a man, said Christian Johnson, a neighbor.
“I came home, they were arguing,” Johnson told WPIX. “I actually stopped to listen, and I heard screaming and the baby was crying. He just kept saying why wouldn’t you pick up the phone, why would you put that stress on me? Why wouldn’t you pick up the phone, why, why? He was screaming, ‘why, why’?”
Police did not release the name of the victim, but neighbors said she was a lawyer and was married.
By Julie Cannold and Lateef Mungin
™ & © 2013 Cable News Network, Inc., a Time Warner Company. All rights reserved.