TOKYO -- A Boeing airliner operated by All Nippon Airways (ANA) sent out a stream of sparks as it made an emergency landing Thursday due to mechanical problems, television pictures showed.

None of the 141 passengers and eight crew members was injured in the incident involving the Boeing-767 in Fukuoka on the southwestern island of Kyushu, the Japanese airline said.

The plane departed for Okinawa but was forced to turn back after a warning message that the landing gear was not properly stored, said an ANA spokesman.

Once the plane landed, a thick trail of golden sparks flew out of its main landing gear.

"We are investigating the cause of the incident," the spokesman said.