The federal space agency said two of its WB-57 aircraft departed from Ellington Field on Wednesday to conduct aerial surveys of the Guadalupe River and surrounding areas in Central Texas, where more than 120 people have died and at least that many were still considered missing as of Thursday.

After flooding caused wreckage across the Texas Hill Country, NASA’s Disaster Program resources were brought in to provide crucial data to aid in the massive ongoing search for more than 170 missing people as first responders sort through catastrophic amounts of debris.