Health concerns are slowing down a caravan of migrants who are heading towards the United States according to an organizer of the group.

He said that there are more than 150 boys and girls who cannot walk anymore and, according to the wire service, there are pregnant women with sores on their feet who are unable to walk either. They estimate that about 90 women are in a critical state.

The Mexican government said they would offer women and children humanitarian visas so they could gain employment, health care and other public services. However, the group has denied the visas because they say there is a lack of resources in Mexico.

The caravan has stopped for the day, but will continue to the U.S. Monday morning.