It happened on Monday inside an apartment in the Bronx, and authorities are hoping surveillance video of the assailants will lead to arrests.
Police say the 60-year-old female victim answered the door for who appeared to be a delivery person holding a box.
The individual at the door, who stated he worked for UPS, was wearing a brown winter hat with "UPS" on the front. When the victim opened the door, the individual pushed her inside the apartment and revealed that he had a silver revolver inside of the box.
WATCH: Raw video of home invasion suspects:
After he gained entry, the second individual joined him.
At gunpoint, they demanded that the woman, her 63-year-old husband Luis Valerio, and their grandchildren - an 8-year-old boy and a 6-year-old girl - use zip ties to bind themselves.
"They were carrying a box, but the box was empty," Valerio said in Spanish. "And below the box, they had a gun and they pushed their way inside."
The two men proceeded to remove property, including two iPhones, an iPad and personal documents.
"The kids were with us, screaming, 'Papa!'" Valerio said. "They were scared. They're still traumatized today."
The men also gained access to a safe and a children's piggy bank with $230, removing more than $7,500 in cash in total.
Then they fled the apartment with the stolen property and cash. The four victims were not injured.
"Thank God nothing happened," Valerio said. "Nothing more than everything they took, papers, documents, everything."
It is unclear why the family was targeted.