OSHA also said that it's investigating a fatality that occurred on June 1 at an Amazon fulfillment center in Carlisle, Pennsylvania.
The incidents show the risks of working at the facilities where everything from electronic gadgets to baby diapers are shipped to millions of customers. Amazon has faced criticism for the treatment of its workers, including from labor unions that have attempted to organize workers at the fulfillment centers.
Mary Osako, a spokeswoman for Amazon, didn't respond to requests for comment.
Chief Executive Officer Jeff Bezos has been spending heavily to increase the Seattle-based online retailer's network of warehouses. In the first quarter, fulfillment expenses climbed 29 percent to $2.3 billion. The company has distribution centers worldwide, including in Beijing and across the U.S. in states such as New Hampshire and Indiana. For this past holiday season, Amazon said it was hiring 70,000 full-time seasonal workers for its fulfillment centers.