Among the potential victims of the Hurricane Harvey are hundreds of thousands of undocumented immigrants who live in Houston and other hard-hit parts of Texas.

The storm is devastating the region just days before a new state law cracking down on sanctuary cities is scheduled to take effect. Advocates say it presents an entirely new set of challenges for a population already reeling from accelerated state and federal enforcement of immigration laws.

As the hurricane loomed, federal authorities and Texas Gov. Greg Abbott (R) said undocumented immigrants should seek shelter from the storm and rising floodwaters. In a joint statement, the U.S. Immigration and Customs Enforcement and U.S. Customs and Border Protection agencies said they would not target undocumented immigrants at evacuation sites, shelters or food banks, and would prioritize “lifesaving and life-sustaining activities” during the storm and its aftermath.

But Oscar Hernandez, a community organizer with United We Dream in Houston, said he knew of undocumented immigrants in the Houston area who were afraid to seek help from shelters and were bunking with neighbors instead. Others are worried about losing their houses or everything they own to floods.