Several sewing needles were found in four turkey sandwiches on a few separate Delta Air Lines flights from Amsterdam to the United States on Sunday.

One person was injured and declined medical treatment after a flight landed in Minneapolis, said a Delta spokeswoman Kristin Baur according to CNN.

FBI and Dutch authorities, Delta Air Lines and Delta’s caterer Gate Gourmet, are still investigating how the needles got into the sandwiches. The needles were discovered in the food on planes heading from Schiphol Airport in the Netherlands to Minneapolis, Seattle and on two flights to Atlanta, Baur 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.

"Delta (DAL.N) has taken immediate action with our in-flight caterer at Amsterdam to ensure the safety and quality of the food we provide onboard our aircraft," the company added.

Needles were found by a passenger on an Atlanta-bound flight, a U.S. air marshal found while flying on another Atlanta-bound flight, and by another had been found aboard on a Seattle-bound flight in a sandwich that had not been served.

Jim Tonjes of Plymouth, Minn., had pierced to the roof of his mouth when he accidentally bit on a 1-inch needle while eating a turkey sandwich, Minneapolis Star Tribune reported.

"I figured it might be a toothpick," he told the paper. "It looked like a sewing needle but without an eye. ... I was in shock. I thought, 'Oh, my God.' It's the last thing you expect in a sandwich."

Jack Drogt, a 55-year-old surgeon from St. Paul, Minn., said he discovered the needle in his meal while taking his third bite.

"I took a few bites, and on the third bite, I hit something hard," Drogt said. "I thought it was a bone and pulled it out. It was a pin about an inch long, sharp on both ends. I called the stewardess over and informed her. She was appropriately surprised and immediately said, 'That's funny - a guy on the other side of the plane just had the same thing happen.' "

A spokeswoman for Gate Gourmet reportedly said that the company had not received any reports of similar cases on any of the other airlines it serves out of Amsterdam, adding that the company did not know where the needles got into the sandwiches, according to The Telegraph.

"We take this matter very seriously, and we have launched our own full-scale investigation," Gate Gourmet said in a statement. The company also said it was "heightening our already stringent safety and security procedures, to prevent any recurrence."