A set of conjoined twins travelling from Brussels to New York died aboard a plane on Thursday off Canada's eastern coast, Canadian police said.
The flight was about 35 minutes off the coast of the city of Halifax when the girls' mother noticed they had stopped breathing, the Royal Canadian Mounted Police (RCMP) said in a press release.
A doctor on board the Delta plane tried to help the babies, but was unsuccessful.
The plane had been diverted to Halifax and Emergency Health Services and the provincial Medical Examiner's office have been notified.
The twins were from Liberia and were headed to the United States to receive medical treatment for an unspecified illness, according to the press release.