MINNEAPOLIS – Delta Air Lines Inc. 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 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.

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 by a catering company. Another sandwich served on the Minneapolis-bound flight also had a needle, Baur said.

After the needles were found, passengers got pizza instead.

Baur said security for its meal production has been increased and it is using more prepackaged food while the investigation continues. The sandwiches were made in the Amsterdam kitchen of Gate Gourmet, and were to be served to business class passengers on Delta flights.