The robbery occurred at about 1:40 p.m. Tuesday at Brookfield Court, a 12-unit housing development at 9507 Edes Ave., Habitat for Humanity spokeswoman Krysta Morgenthaler said.
Four suspects, one armed with a gun, robbed eight workers at the site and then fled in two cars, police said.
A shot was fired during the robbery but no one was hit, Morgenthaler said.
One of the victims was pistol-whipped but refused medical attention, according to police.
Morgenthaler said no one else was hurt in the robbery.
The suspects got away with the victims' wallets, phones and some tools, according to Morgenthaler.
No arrests have been made, police said Thursday.
The former president and his wife Rosalynn are scheduled to visit the Bay Area next week to kick off the 30th annual Jimmy and Rosalynn Carter Work Project, Morgenthaler said.
After an opening ceremony Sunday night at the Paramount Theatre in Oakland, the Carters will be at the Brookfield Court development -- which is scheduled to open in early 2014 -- to help build the homes on Monday, she said.
The Carters are scheduled to be at the site from 8:30 a.m. to sometime in the early afternoon, according to Morgenthaler.
"We have already increased private security and are working with police to ensure people are safe," Morgenthaler said.
Carter will then spend Monday evening at a private home in Saratoga for a fundraiser before assisting with the rebuilding of structures to provide shade for picnickers at Lake Cunningham Park in San Jose on Tuesday.
Upon leaving the Bay Area, Morgenthaler said Carter is scheduled to make stops in Denver and New York.