What appeared to be sewing needles were found in sandwiches served in business-class cabins on four Delta Air Lines flights to the U.S. from Amsterdam on Sunday, the airline confirmed.

The Wall Street Journal reports a passenger on one of the flights was injured but declined medical treatment from paramedics after the plane landed in Minneapolis, Delta said.

The airline said it requires all of its caterers "to adhere to strict criteria in order to offer our customers the very best onboard meals. The safety and security of our passengers and crew is Delta’s No. 1 priority."