The shop's employees decided to close the doors and call the police.
"We saw him walk past the shop; he stopped in front of the automatic doors, which opened, and he walked in very quietly," employee Helene said as quoted by the Le Telegramme newspaper.
"He was not at all aggressive, he was just doing his thing," she added.
One of the visitors managed to take a photo of the curious alpaca, who possibly just wanted to buy a pair of glasses.
Half an hour later, the alpaca's owner arrived to collect the animal.
Alpacas are indigenous to South America's Andes Mountains and are sometimes confused with llamas. They have been domesticated for thousands of years, and are valued for their fleeces, which are used to make wool. Alpaca wool has very dense, high-quality fibres and is valued for its warmth and for being hypoallergenic.