Delta Air Lines Inc said it was working with federal authorities after what appeared to be sewing needles were found in food on four U.S.-bound flights that left Sunday from Amsterdam, injuring one passenger. The needles were found in sandwiches made by the airline’s Amsterdam caterer, Gate Gourmet, Delta spokeswoman Chris Kelly said in an email Monday. The FBI and Netherlands officials are investigating, Delta said. "Delta is taking this matter extremely seriously and is cooperating with local and federal authorities who are investigating the incident," the airline said in a statement.