Houston Mayor Sylvester Turner says he is imposing a midnight to 5 a.m. curfew in order to ensure public safety.
Turner says at a news conference Tuesday that there is no reason for people to be on the streets during those hours.
Police Chief Art Acevedo said violators will be stopped, questioned, searched and arrested.
There have been scattered reports of looting during the flooding from Tropical Storm Harvey.
"So word to the wise: Don't come to Houston," Acevado said on Tuesday, "because you're going to be caught.”
“And I guarantee you when you take advantage of people and prey on them in these circumstances, that's despicable behavior and we're all going to push hard to make sure you don't see the sunlight anytime soon."