The group, called "Little by Little Haiti," was on its seventh trip to the island with medical supplies and equipment for health screenings when the massive tremor hit last week.
"I think we were just confused. Many of us had never been in an earthquake before," said emergency room nurse Heather Vruggink.
Of the 23 members in Haiti, nearly half are trained medical staff.
After the quake, Vruggink said she too charge of some of the less experienced nurses and headed to a hospital that had only one doctor, few nurses and barely any medical supplies.
"We had a bag of scrubs, and we started ripping off the scrubs so we could triage the patients," said nurse Amy Kaplan.
With the help of several non-medical volunteers, the group helped more than 100 victims.
"I think many of them lived because we were able to give them antibiotics, and able to give them fluids, and able to stitch them up," Vruggink said.
The group had originally traveled to Haiti on Jan. 6 to treat people in a village just 12 miles outside of Port-au-Prince. What is normally a five or six hour flight back to Chicago took more than a day. Still, many didn't seem to mind the delay because they were able to lend a helping hand.
"This is the worst trauma that I've ever seen in my entire life," said Tricia Wirth, a nurse at Children's Memorial Hospital.
"There was a reason for us to be there. We were able to do something for people that in other ways would have had no help, no hope," said Mary Mulhall.
Many said they wished they could go back and continue to help out.
Complete Coverage: Devastation in Haiti