Connecticut ? Family members Thursday mourned three children and the woman they say gave her own life in a failed attempt to save them as her minivan rolled down a hill and sank in a park pond.

Michelle McIntosh, 39, died Wednesday along with her 2-year-old son, David, and 3-year-old family friend Julia Boyd. Her nephew, Jayden Wilson, 6, died Thursday at Yale-New Haven Children’s Hospital, where he had been in critical condition.

McIntosh’s husband, David, said his wife had planned to find a spot for their Fourth of July picnic and then return to the house, less than a half-mile from Beardsley Park, to get him and their three other children. She had stopped the minivan to talk with friends in another car about where to set up, police said.

Seconds after she stepped out, the van began to roll, police said. She chased it and was dragged for a short distance, losing her shoes as she climbed in and tried to stop the vehicle, police said. It rolled 60 or 70 yards down a steep hill and into a pond, where it was submerged in 15 to 20 feet of water for up to 25 minutes.