At a Saturday court hearing, prosecutors said 32-year-old Ebony Wilkerson was a flight risk and was a danger to the community, herself and her unborn child. Authorities confirmed she is 27 1/2 weeks pregnant.
Volusia County Court Judge Shirley Green set her bond at $1.2 million. A date for an arraignment was not released.
Friday, police charged Wilkerson with three counts of attempted murder and three counts of child abuse causing great bodily harm.
According to Volusia County Sheriff Ben Johnson, Wilkerson drove her minivan into the ocean in Dayton Beach, Fla. on Tuesday. She got out of the car after leaving her kids inside.
Police said a beach safety officer had to fend her off as he was trying to rescue the kids from the van. The children are ages 3, 9 and 10.
"She tried to stop someone from going into the vehicle. That's one of the reasons you have a premeditated first-degree murder," Johnson said at a Friday news conference.
Upon investigation, authorities determined that Wilkerson did not suffer from mental illness or was under the influence of alcohol or drugs at the time of the incident.
Police said after being taken to the hospital, Wilkerson's children told them "Mom tried to kill us." The oldest told officers that Wilkerson brought them to the beach "so we could die" and that she was taking them to a "safer place." The oldest child tried to steer the car out of the surf, but Wilkerson drove into the water.
Family members of Wilkerson, who is from Cross, S.C., had called police earlier in the day because they were concerned about her. Wilkerson, however, told police that she was going to a domestic abuse center with the kids.
Instead, police say she drove her Honda Odyssey minivan to Daytona Beach. She rolled up the windows and told her kids to go to sleep. Witnesses saw her gunning for the surf and ran to stop the woman. Bystanders say the three kids were screaming for help.
Stacy Robinson, one of the men who rushed up to the van, said a back window was still cracked open and he was able to reach in and open the door. Other bystanders and lifeguards arrived and helped rescue the children from the sinking car.
The Associated Press and ABC News contributed to this report