"Oh my gosh. That's so sad. I ran into him from time to time in the hallway," said one resident who said he moved into the building last fall. "He looked just like he did in his photos. Such a nice young, vibrant man."
He lived on the fifth floor with a roommate, who was also a Google engineer.
"They were like two peas in a pod," another neighbour said.
Krulcik's Linkedin page says he began working at Google in August after serving as an intern in the summer of 2017.
He graduated from Carnegie Mellon University last spring with a degree in computer science.
Google representatives did not immediately return emails seeking comment.
- additional reporting AP