A company spokesperson said she did not know the cause of the outages.
The company apologized for the outage in a note to users on its home page.
"We're sorry, but our store is closed temporarily," the note said. "We expect to be back soon. We apologize for the inconvenience, and thank you for your patience."
Amazon suffered a similar downtime in July, when its site was down for about 35 minutes just days after it launched its new toys and electronics stores. Last year, the company experienced a pair of multi-hour outages, including a 12-hour outage in January 1998.