Ngoc Do, the driver, says she and her cousin were lost when she accidentally drove off a boat ramp in Elgin B. Robertson Park late Friday night.
"I was talking on the phone with my dad, asking him how to get out, and then I heard her screaming, and I realized there was water in front of me," she said.
Rockwall County Sheriff's Deputy Keven Rowen was captured on his squad car's dashboard camera saving the lives of the two women.
On Monday, Dallas city crews installed new warning signs around the lake.
The Parks and Recreation Department is also considering putting barricades, road humps and reflective signs near the boat ramp.
The city of Dallas said it is evaluating boat ramp's existing conditions and developing a plan to enhance visibility.
The enhancements deemed most appropriate would be implemented as soon as possible, the city said.
Do and her cousin, Nhi Tran, said the accident happened while it was late and dark.
They got lost after dinner while driving home to Garland.
Neither cousin knows how to swim.
"I was thinking I would die, for sure," Tran said.
Do said the water was up to her neck when she saw the lights from Rowen's squad car.
"I think it was God who sent the officer to us," she said.
Rowen waded into the frigid waters to rescue the women.
"As I'm busting out the window, their heads are pressed against the roof, trying to get air," he said. "They were screaming, 'Hurry, hurry.'"
Rowen carried both women out of the car in his arms. The Honda Civic sunk seconds later.
"I have to thank him so much, because he was there at the right moment, right time," Do said.
Rowen said it was the second time in as many months that a car has driven off a boat ramp at Lake Ray Hubbard.
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