Philadelphia

At least seven children are among the dead, an official from the Philadelphia Fire Department told reporters.

The blaze began at around 06:00 local time (11:00 GMT) in a public housing block in the north of the city.

Deputy Fire Commissioner Craig Murphy told reporters it was one of the worst fires he had ever seen.

"We plan on making sure that this tremendous loss of life did not happen in vain," he said on Wednesday.

He added that eight other residents had managed to escape the building.

Francis spent time with fellow Argentinians Catire Walker and Noel Zemborain and their four children, talking about their visit and praying.

Zemborain told the Associated Press that Francis told her that they were crazy to drive so far with their children. She said it was like meeting an old friend and Francis hugged the children.