A Florida “hero” mom died after using all her strength to keep her 4-year-old son above water when he fell into the St. Johns River, allowing rescuers to pull the boy to safety, authorities and her family said.Nicole Grayson, 43, jumped into the river after her young son fell into the water at Ed Stone Park, west of DeLand, around 4 p.m. Saturday, according to the Volusia Sheriff’s Office.Investigators said the child had been playing with an unidentified object near a wooden fence along the river’s edge when he dropped it over the barrier. The boy fell into the river while attempting to retrieve it.OFF-DUTY ICE OFFICER RELIES ON ‘SIXTH SENSE’ TO SAVE DROWNING CHILD BEFORE DELIVERING MESSAGE TO CRITICSGrayson immediately went in after him.”My guess is he was trying to get it. He slipped in the water, deep, he slipped away in the water,” Grayson’s oldest son, Dafino Devega, told FOX 35. “And then my mom, I guess she panicked, and she went in the water and tried to save him.”CROCODILE ATTACK HORROR UNFOLDS AS COUPLE TRIES TO SAVE VICTIM: ‘WE FELT SO HELPLESS’As Grayson struggled to keep her son above the surface, a witness at the park flagged down a passing boater, who threw two life preservers toward the mother and child, the sheriff’s office said.Grayson eventually became submerged while continuing to hold her son above the water.A frantic 911 caller told dispatchers that rescuers had managed to reach the child but were still struggling to recover his mother.FIREFIGHTERS, POLICE PULL YOUNG WOMAN FROM SEWAGE-FILLED RAVINE AFTER DAYS TRAPPED IN 104-DEGREE HEAT”Hey 911, can you come to Ed Stone Park?” the caller said in audio obtained by FOX 35. “We have a mother that’s drowned, and we got the baby, but we can’t get the mama.”SEND US A TIPThe boater maneuvered close enough to pull the 4-year-old aboard. The boy was unharmed, according to authorities.Witness Jon Reaka said Grayson appeared to expend all her energy ensuring her son survived.”She spent all her energy trying to get her kid up over the edge,” Reaka told FOX 35.Reaka jumped over a railing and onto the boat, where he helped pull Grayson from the river. She was unresponsive when she was brought aboard.GET BREAKING NEWS ALERTS”I jumped over the rail, jumped onto the boat and pulled the lady up onto the boat and, you know, we started CPR — I started CPR and mouth-to-mouth immediately,” Reaka said.Emergency medical personnel took over lifesaving measures after arriving at the park. Grayson was rushed to a hospital, where efforts to revive her continued for several hours.She died in the intensive care unit around 10 p.m. Saturday, the sheriff’s office said.LIKE WHAT YOU’RE READING? CLICK HERE FOR MORE”I tried everything I could do to save her,” Reaka told FOX 35. “You know, I feel horrible. I mean, it’s so sad what happened.”Grayson was a mother of six whose final act reflected the fiercely protective way she had lived, her family said.”That’s the type of mom that she was; she was a hero,” Devega said.”My mom, she was a strong woman,” he added. “She would do anything to keep her kids safe.”CLICK HERE FOR MORE U.S. NEWSFOLLOW US ON XVolusia County Sheriff Mike Chitwood praised the witnesses and boater who rushed to help Grayson and her son.”Sheriff Chitwood and the entire Volusia Sheriff’s Office send sincere thanks all who jumped in to help with the rescue, and deepest condolences to Ms. Grayson’s family and friends for their loss of a mother who gave her life to save her son,” the department said in a statement.GOT A TIP?Chitwood said Grayson would be remembered as a hero, “not just because of her final heroic act, but because she was a mom who would do anything for her kids.”