At least one person has died during rescue operations as “life threatening” flooding takes hold in south-central Texas, where up to 20in of rain have already fallen in some areas – just one year after the same region endured catastrophic flooding that killed more than 100 people.

Flash flood emergencies were issued on Thursday for parts of Kerr and Uvalde counties, where emergency crews performed water rescues, as well as areas around the Guadalupe River and the Pedernales River, according to morning updates from the National Weather Service (NWS).

Rescuers have been plucking stranded drivers and people trapped in homes since floodwaters began rising quickly overnight Thursday.

“This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW!” reads an update from the NWS in San Antonio. “Life threatening flash flooding of low water crossings, small creeks and streams, urban areas, highways, streets and underpasses.”

Texas’s governor, Greg Abbott, said in a press conference on Thursday: “There has been one loss of life now, and that happened overnight.

“I am informed that the loss of life is not a camper,” he said, noting that more than 70 people had been rescued. “Our number one focus is saving lives.”

Drones and helicopters are flying over the region still recovering from devastating floods just a year ago, the governor said.

Flash flood warnings were also in effect for parts of Kinney, Maverick and Zavala counties, among others close to the border with Mexico and in the Texas Hill Country near San Antonio.

A line of storms moving through the region has brought heavy rainfall, causing the Guadalupe River at Comfort, Texas, to rise more than 30ft in a few hours overnight on Thursday. Shelter-in-place orders have been issued for residents in Kerrville and Uvalde, and a broader flood watch remains in effect until Thursday evening.

The catastrophic weather comes just a year after devastating floods during the Fourth of July weekend in the Texas Hill Country killed more than 100 people, including 25 girls and two counselors at Camp Mystic. The Christian girls’ summer camp was located on the banks of the Guadalupe River, where a flash flood emergency was once again in effect on Thursday.

“Our primary focus right now and throughout the remainder of this torrential rain is saving lives,” said Texas’s governor, Greg Abbott, in a statement on Wednesday.

Thunderstorms have produced up to 20in of rain in the Uvalde area over the previous 48 hours, while 3-12in of rain have fallen across parts of Bandera, Kerr and Real counties, with officials warning drivers to avoid crossing flooded roads.

“All major highways and many city streets are CLOSED due to flooding and water over the roadway,” the Uvalde county office of emergency management wrote in a post on social media on Thursday. “Please remain at home unless you are in immediate danger or your location is no longer safe.”