Thousands of Central American migrants crossing Mexico toward the United States in a caravan have resumed their long trek, walking about 12 hours to their next destination.

Carrying their few belongings on their backs -- many with babies pressed to their chests or holding their children by the hand -- they left at dawn after taking a one-day break to rest, bathe and nurse aching and injured feet.

"I miss my country. I'm not doing this because I want to. No one wants to leave their home to go to a place they don't know. But sometimes necessity pushes us to do this, because of what's happening in our countries," said Delmer Martinez, a migrant from El Salvador.