Officials issued a warning Wednesday after disturbing reports surfaced of people impersonating Homeland Security special agents and telling residents to evacuate in order to rob their homes in the wake of devastating flooding from Harvey.

The city of Houston said people should ask anyone knocking on their doors for official badges and credentials with their name and organization. The city's statement also noted that, during Harvey relief efforts, U.S. Immigration and Customs Enforcement is not conducting immigration enforcement operations in the area.

The National Weather Service downgraded the storm to a tropical depression late Wednesday.

Officials for Homeland Security Investigations said there were “disturbing reports” that some people were pretending to be HSI special agents, knocking on doors and telling residents to evacuate -- and then robbing their homes once they are empty.

“Real HSI officials wear badges that are labeled ‘special agent,’ which members of the public can ask to see and verify,” read a statement provided to Fox News. "ICE officers with Enforcement and Removal Operations also wear badges labeled with ERO Officer. They also carry credentials with their name and organization.”

“Members of the public who receive such visitors should ask to see these properly labeled badges, and their credentials.”

The storm has killed at least 23 people, according to officials in the area. Rescue crews found several more bodies Wednesday as floodwaters across much of the city started to recede.

HSI officials also said in their statement their officers and special agents would be conducting hurricane relief operations with other local law enforcement agencies.

ICE said Wednesday it is not undertaking immigration enforcement operations in storm-affected areas.

The agency said it had assigned about 150 employees from around the country to help with disaster relief efforts in Houston, and it is prepared to send more employees if needed.

There are 139 agents and officers from Atlanta, Chicago, Dallas, Detroit, El Paso, Houston, Washington, New York, San Diego and Tampa on scene, according to ICE. The agents are on 25-member teams that answer to the Federal Emergency Management Agency.

Fox News' Jake Gibson and The Associated Press contributed to this report.