• High body temperature and a lack of sweating
• Nausea and vomiting
• Rapid breathing and a racing heart rate
• Headache and muscle cramps
• The body going into shock, which is indicated by very low blood pressure, blue lips and nails, and cool, clammy skin.
Source: Mayo Clinic
Paramedics, doctors and nurses "pulled out every trick they could think of" in desperate attempts to cool two young brothers' bodies that had reached or surpassed core temperatures of 105 degrees on June 28, according to the Bradley County Medical Examiner's office.
But the dozens of medical staff surrounding 5-year-old Leland and 3-year-old River Bates, the CPR, the organ-stabilizing medications and the gallons of cooling fluids pumped into the boys' bodies all were too late.
River was gone within 45 minutes after his mother's first call to 911 at 2:44 p.m. Family members say Leland was declared brain-dead that night.
Eric Blach, lead investigator with the medical examiner's office, could not release the boys' exact core temperatures. He said the hospitals that treated the boys recorded the temperatures, so the information is confidential.
That information and the boys' toxicology reports are now being analyzed at the state level.
Bradley County Sheriff's Office spokesman Bob Gault said Wednesday there was no new information in the investigation, but that detectives still are compiling information and conducting interviews.
The boys' mother, Tasha Moses, initially told first responders she thought the boys had drowned. She later told investigators she left the boys unattended outside their rural Cleveland, Tenn., home in 101-degree heat, and found them unconscious 45 minutes later.
Recordings of the 911 calls have not yet been made available because of the pending investigation.
Moses drove them more than 1.5 miles to her father's house before calling 911, saying she didn't have a working phone at her house.
Medics detected a pulse while treating Leland, so he was flown to Children's Hospital at Erlanger for treatment.
But River's condition was too delicate. More than a dozen medical staff members and even a surgeon crowded into the SkyRidge Medical Center emergency room to try to save him, Blach said.
"They were doing absolutely everything they could to keep the body cool," he said.
Blach said cases of hyperthermia -- the cause of death for both boys -- are "exceedingly rare" in Bradley County.
The county medical examiner, Dr. Jeffrey Miller, has described hyperthermia as having a "cascading effect." Once extreme heat damages the brain, other vital organs aren't able to function and the body begins to shut down.
"He was basically gone by the time he got there [to the hospital]," said the boys' paternal grandmother, Linda Bates. After viewing the 3-year-old's lifeless body that day she went to Children's Hospital to be with Leland.
The boys' parents are divorced, but both of them and other family members were able to hold and say goodbye to the comatose Leland before he slipped away.
"It just seemed so pitiful just to watch him," Bates said through tears Wednesday. "I just told him I loved him."
Bates and other family members say the maternal and paternal sides of the boys' families -- which used to coordinate schedules to make sure the boys were being cared for -- have been split apart since their deaths.
"There's a lot of hearsay going around, and it's hard to know exactly what happened," said the boys' great-great-grandmother, Debbie Burgess. "And everyone is just so sad. Both just gone so quick -- at the same time."