The department was working with around a dozen supporting agencies to find the girl, who was last seen at about 4 p.m. Monday.
“We remain deeply committed to finding this child and bringing her home,” the department said.
The missing child was a student from Brenham Elementary School and support services will be available for students and staff, according to a Brenham Independent School District social media post.
“Our hearts are with the student’s family, and we ask our community to keep them in your thoughts and prayers during this incredibly difficult time,” the district said.
The next round of severe storms could bring as much as 6 inches (15 centimeters) of rain Tuesday to parts of southeastern Texas, according to the National Weather Service in Houston.
The weather service also warned of a series of strong rip currents and flooding along Gulf-facing beaches, especially during high tides.
A large swath of the state, along with parts of New Mexico, Oklahoma, Arkansas, Louisiana and Mississippi were under a National Weather Service flood watch early Tuesday.
Just last week, storms drenched much of southern Oklahoma and northern Texas, flooding and washing out roads and causing hundreds of flights to be canceled or delayed at major airports.