"Firefighters and paramedics administered medical aid but were unable to revive the victim," the police said.
Facebook acknowledged the incident had occurred in a statement released through a spokeswoman.
"We were saddened to learn that one of our employees passed away at our Menlo Park headquarters earlier today," the spokeswoman said.
"We're cooperating with police in their investigation and providing support to employees. While the family is being notified, we have no information to share. We hope to provide an update when we learn additional information from law enforcement."
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
OR IF YOU NEED TO TALK TO SOMEONE ELSE:
• 0800 543 354 (0800 LIFELINE) or free text 4357 (HELP) (available 24/7)
• https://www.lifeline.org.nz/services/suicide-crisis-helpline
• YOUTHLINE: 0800 376 633
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757 or TEXT 4202