THE AREA AND HOW PEOPLE COPED WITH THE ISSUE FOR HOURS. GOOD EVENING. A HEARTBREAKING TRAGEDY IN SUFFOLK COUNTY. >>> A COMMUNITY READING, THE LOSS OF TWO YOUNG SISTERS WHO WANDERED FROM HOME AND DROWN. WE SPOKE WITH NEIGHBORS DESPERATELY TRIED TO FIND THE GIRLS BEFORE IT WAS TOO LATE. >> Reporter : A SIGN OF CELEBRATION, THE FIRST DAY OF KINDERGARTEN LAST WEEK. NOW THERE IS GRIEVING INSIDE THIS TOWNHOUSE. SISTERS, 4-YEAR-OLD TWINS -- THE 4-YEAR-OLD AND 2-YEAR-OLD SOMEHOW GOT UPSTAIRS AND AFTER THE UNIT AND WANDERED TOWARD THE POND, THE CENTERPIECE OF THE TOWN HOUSES WHICH STRADDLES THE PICTURESQUE BODY OF WATER. >> THE MOTHER WAS FRANTIC LOOKING FOR THEM. THE ENTIRE NEIGHBORHOOD CAME OUT LOOKING FOR THEM. >> Reporter : A HEART WRENCHING SCENE, THE FRANTIC EFFORT TO CALL 911 AND ENLIST HELP FROM THOSE ON THE BLOCK WHEN THEY REALIZED THE GIRLS GOT OUT. >> HOW DO THESE THINGS HAPPEN, THAT IS WHY THEY ARE CALLED TRAGIC ACCIDENTS. THEY HAVE A GATE AND ALL OF THE SAFETY PRECAUTIONS. I HAVE NEVER SEEN THE CHILDREN LEFT UNATTENDED. >> Reporter : GOOD SAMARITANS MAYBE IMPECCABLE DISCOVERY IN THE POND MOMENTS ARE. THE SISTERS COULD ALL BE SAVED BY RESPONDING POLICE WHO HAD NOT SAID HOW THEY BELIEVE THE CHILDREN WERE ABLE TO LEAVE THE APARTMENT. >> POSSIBLE ONE FELL IN AND THE OTHER TRIED TO HELP. IT IS UNIMAGINABLE. >> Reporter : SECTIONS OF THE POND ARE FENCED BUT OTHERS ARE NOT. THEIR SIGNAGE TO KEEP OUT OF THE WATER. >> EVERYBODY IN SHOCK. THIS IS A BEAUTIFUL PLACE TO LIVE. A LOT OF US CHOOSE TO LIVE HERE BECAUSE OF THE LAKE AND EVERYTHING AND THE WATER. IT SHEDS A DIFFERENT LIGHT ON A. >> Reporter : A FUNDRAISER FOR THE FAMILY SAYS THE FATHER IS STUCK IN INDIA WITH VISA ISSUES. THEY'RE WORKING ON HELPING HIM GET HOME FOR THE CHILDREN'S FUNERAL. >>> WET DID TOREAC