(Kirit Radia/ABC News)

GENEVA - Secretary of State John Kerry took a break from his effort to halt the advance of Iran's nuclear program to buy his wife some Swiss chocolates. In the process, he apparently trapped employees and shoppers in neighboring stores in downtown Geneva.

Kerry left the negotiations at the Intercontinental Hotel this afternoon to swing by the famed Auer Chocolatier, an artisanal shop founded in 1939 where the chocolates are made fresh daily. The shop's website proudly declares that it is in its fifth generation of family ownership and features a photo of Arnold Schwarzenegger visiting the store.

There the cheapest individualized box, weighing just over half a pound and consisting of about 20 pieces, costs 29 Swiss Francs, or nearly $32. The store specializes in truffles and pralines, many with nutty fillings. Employees were eager to highlight their chocolate-covered almonds with a cocoa powder dusting.

An Auer employee giggled when asked about her encounter with Kerry, telling ABC News he was "very nice" and spoke "perfect French." He posed for a photograph with the staff before leaving.

The employee said she was not allowed to talk about Kerry's visit, but revealed that he purchased three boxes. The employee said he chose the shop because it was his wife's favorite.

The visit was brief, but while he was there Kerry's security team would not allow people to enter or leave adjacent shops, including the neighboring L'Occitane store, according to an employee there.

Earlier in the day, Kerry's staff confirmed that he left to buy chocolates for his wife. A staffer later told ABC News by email that the chocolates were for his family's Thanksgiving dinner but did not provide any more details. In a breach of protocol, reporters that are assigned to follow Kerry everywhere while he is traveling overseas were not notified about the side trip until after he had departed and were left at the hotel.

Kerry arrived in Geneva this morning to try to close a deal, under which Iran would temporarily suspend and even roll back elements of its nuclear program. In exchange, the United States and its negotiating partners - Great Britain, France, Germany, Russia, and China - would release a modest amount of frozen funds. The two sides haggled over whether Iran has the "right" to enrich uranium, as well as what happens to Iran's plans to build a heavy water nuclear reactor near the city of Arak, which could provide a plutonium-based path to a nuclear weapon if Iran chose to pursue one.

With the prospect of additional Congressional sanctions on Iran looming, negotiations continued past midnight as diplomats tried to reach an agreement.