Washington - Two New York senators on Thursday said they will seek posthumous US citizenship for the victims of a horrific shooting spree last week at an immigration centre in Binghamton, New York.

A lone gunman killed 13 people last Friday when he entered Binghamton's American Civic Centre, which offers services to refugees and immigrants and classes to prepare them for US citizenship tests.

Eleven of the victims were immigrants seeking citizenship, including four from China and others from Haiti, Vietnam, Iraq, the Philippines, Pakistan and Brazil.

Senators Charles Schumer and Kristen Gillibrand said they had introduced legislation in Congress that would authorize the government to provide honorary citizenship to those who were killed.

"The people who were so cruelly and suddenly taken from us in Binghamton were the very epitome of the huddled massive yearning to breathe free who have made America a great nation," Schumer said in a statement.

"Fulfilling the dream of American citizenship is the least we can do," he said.