Three toddlers were in critical condition after nearly drowning when they fell into a pool at a North Tustin home where they were under the care of a baby sitter. The children were identified as Jonathon Derek Weston, 22 months; Melissa Dianne Polsfoot, 19 months, and Arthur Matthew Griese, 14 months. Doctors said they would know within 72 hours whether any had suffered permanent brain damage. Authorities immediately launched an investigation into the baby-sitting arrangement at the home of Orvel Brooks. County social worker Karen Rater joined sheriff’s deputies in the investigation but said it had not been determined if Brooks or a member of his family had, or needed, a license to care for the children. One unidentified mother left the house distraught, asking herself: “How did he get in the pool? There was a six-foot fence!” Deputies released no information on how the toddlers fell into the pool, or how long they were in the water before Brooks found them.