*This story was updated Thursday evening to reflect new information from the evacuation team

The process to evacuate ten infants from the neonatal intensive care unit of Driscoll Children's Hospital in Corpus Christi and bring them to North Texas began Thursday afternoon.

Hospital officials in South Texas worried the safety of the babies could be at risk as Hurricane Harvey, forecast to become a Category 3 storm, approaches the Gulf Coast.

By late Thursday six of the infants had arrived at Fort Worth's Cook Children's Medical Center. All of the infants are expected to be in North Texas by early Friday morning.

1 / 4Paramedics transport one of ten babies in a Neonatal Intensive Care Unit from a Cook Children's Hospital airplane to an ambulance on Thursday, August 24, 2017 at Teddy Bear Transport hanger at Fort Worth Meacham Airport in Fort Worth, Texas. The babies were evacuated from Driscoll Children's Hospital in Corpus Christi ahead of Hurricane Harvey. (Ashley Landis / Staff Photographer) 2 / 4One of ten babies in a Neonatal Intensive Care Unit is transported from a Cook Children's Hospital airplane to an ambulance on Thursday, August 24, 2017 at Teddy Bear Transport hanger at Fort Worth Meacham Airport in Fort Worth, Texas. The babies were evacuated from Driscoll Children's Hospital in Corpus Christi ahead of Hurricane Harvey.(Ashley Landis / Staff Photographer) 3 / 4Paramedics transport one of ten babies in a Neonatal Intensive Care Unit from a Cook Children's Hospital airplane to an ambulance on Thursday, August 24, 2017 at Teddy Bear Transport hanger at Fort Worth Meacham Airport in Fort Worth, Texas. The babies were evacuated from Driscoll Children's Hospital in Corpus Christi ahead of Hurricane Harvey. (Ashley Landis / Staff Photographer) 4 / 4Paramedics transport one of ten babies in a Neonatal Intensive Care Unit from a Cook Children's Hospital airplane to an ambulance on Thursday, August 24, 2017 at Teddy Bear Transport hanger at Fort Worth Meacham Airport in Fort Worth, Texas. The babies were evacuated from Driscoll Children's Hospital in Corpus Christi ahead of Hurricane Harvey.(Ashley Landis / Staff Photographer)

The babies are dependent on ventilators, and a power outage could threaten their oxygen supply. They are the "sickest of the sick," said Debbie Boudreaux, Cook Children's director of transport.

"Those are the patients you need to get out quick. And that’s our focus right now," she said.

Transport teams including nurses and respiratory therapists departed North Texas on jets starting around 3 p.m. Thursday afternoon.

Each aircraft could handle about two patients at a time. The health system partnered with other air medical providers to conduct the evacuation.

Children's Health in Dallas also sent two planes.

Children's Health will transport four of the 10 infants. All of the babies will remain in Fort Worth until they are able to return to Corpus Christi.

Hurricane Harvey is expected to bring life-threatening storm surge and flooding up to 10 feet above ground level, damaging winds and upwards of 20 inches of rain in some areas, according to the National Hurricane Center.