The girls had a table set up outside an Albertson's grocery store in Escondido. They say a man came out of the store, grabbed their donation box, and ran away.
The troop leader chased after him but fell while trying to grab the money. She says the crime is especially bad because the money was for Operation Thin Mint, which provides Girl Scout cookies for servicemen and women overseas.
"It wasn't so much about the money. It was 45 or 50 bucks. It was about the principal of it," said Erin Fullerton. "He stole from the Girl Scouts and the soldiers and all these people who donated the cash. How low can you go, right? How low can you go?"
Fullerton says since the crime, other people have donated more than $300 to buy cookies for troops serving abroad.
The troop leader also got the thief's license plate number and is hoping that will help police track him down.