MINNEAPOLIS — Delta Air Lines and the FBI are trying to figure out how needles got into turkey sandwiches served aboard four flights from Amsterdam. One passenger was injured.

The airline said that what appear to be sewing needles were found in five sandwiches on Sunday. One passenger on a flight to Minneapolis was injured, but the passenger declined to get medical attention, according to Delta spokeswoman Kristin Baur. The other needles were on two flights to Atlanta and one to Seattle.

The FBI’s Atlanta office has opened a criminal investigation into the matter, the agency said in a written statement.

Baur said flight attendants stopped serving the sandwiches as soon as the needle was discovered. Messages went out to other flights en route from Amsterdam, where the sandwiches had been prepared.

After the needles were found, passengers got pizza.

Baur said security for its meal production has been increased and it is using more prepackaged food while the investigation continues.

“Delta is taking this matter extremely seriously and is cooperating with local and federal authorities who are investigating the incident. Delta 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 airline said in a written statement.