People interact with staff members of the Christmas-themed train Caltrain in Millbrae, California, the United States, Dec. 8, 2019. Staff members of the Christmas-themed train Caltrain are dressed in Christmas-themed costumes to greet the residents. (Photos: Xinhua)

People interact with a staff member of the Christmas-themed train Caltrain in Millbrae, California, the United States, Dec. 8, 2019. Staff members of the Christmas-themed train Caltrain are dressed in Christmas-themed costumes to greet the residents.

A staff member of the Christmas-themed train Caltrain shows up in a Santa Claus costume in Millbrae, California, the United States, Dec. 8, 2019. Staff members of the Christmas-themed train Caltrain are dressed in Christmas-themed costumes to greet the residents.

People interact with staff members on the Christmas-themed train Caltrain in Millbrae, California, the United States, Dec. 8, 2019. Staff members of the Christmas-themed train Caltrain are dressed in Christmas-themed costumes to greet the residents.

People interact with a staff member of the Christmas-themed train Caltrain in Millbrae, California, the United States, Dec. 8, 2019. Staff members of the Christmas-themed train Caltrain are dressed in Christmas-themed costumes to greet the residents.