CENTENNIAL, Colorado (AFP) - Police described harrowing scenes after the Colorado theatre shooting on Monday, including blood "sloshing" in one officer's car, while the alleged gunman was strangely relaxed when arrested.
A number of officers choked back tears at a preliminary hearing for James Holmes, accused of killing 12 people and injuring dozens more at a midnight screening in Aurora, outside Denver, in July.
As relatives pulled out their handkerchiefs in court, another first responder recalled finding the youngest victim of the shooting, a six-year-old girl, with no pulse amid the carnage.
They were speaking at the start of a week-long hearing to decide whether there is enough evidence for a full trial of the 25-year-old, accused of opening fire at at the premiere of the Batman movie The Dark Knight Rises.
The Aurora massacre revived the perennial US debate over gun control - an issue re-ignited even more intensely by last month's shooting of 20 young children at a Connecticut elementary school.
Officer Justin Grizzle, a former paramedic, said he almost slipped over in a "huge amount of blood" as he entered the back entrance to the Century 16 movie theatre.
As ambulances struggled to cope with the scale of the slaughter, Mr Grizzle described how he transported six critically ill victims in four trips to area hospitals.
"I realized later that as I was slowing to make turns, I could hear blood sloshing in the back of my car," Mr Grizzle testified, choking as he remembered the night.
One man sitting in the officer's car along with his stricken wife had to be restrained to keep from jumping out to go and look for the couple's daughter Veronica, who at six became the shooting's youngest victim, Mr Grizzle said.
Sergeant Gerald Jonsgaard, one of the first officers on the scene, described finding Veronica Moser-Sullivan as he entered the theater shortly after midnight on July 20.
"She had been carried down from the top to the front of the theatre. I checked for a pulse. She was dead," he said, voice breaking.
A colleague said he felt a pulse, but the child was declared dead on arrival in hospital.
Holmes, sporting dark brown hair and a full beard, was led into court in handcuffs at the hearing expected to uncover more details about the shooting.
Clad in dark red prison scrubs, Holmes - who had bright orange hair when he first appeared in court shortly after the shooting - stared straight ahead and talked to no one.
Aurora policeman Jason Oviatt told the court how he at first thought Holmes was another officer when he arrived with dozens of other police in response to 911 emergency calls about the shooting at a screening of the new Batman film.
Holmes had his hands on the top of a white car at the back of the building, and as Mr Oviatt approached, he saw he was not a fellow officer.
"As I got closer the man was just standing there, not moving. The overall picture didn't match a police officer as I got closer," said Mr Oviatt.
Holmes offered no resistance when he was ordered to put his hands up.
"He was completely compliant... He was very relaxed, there weren't normal reactions to anything... He was very detached," MrOviatt said, adding: "He seemed to be out of it, and disoriented."
Witnesses said Holmes threw smoke bomb-type devices before opening fire randomly with weapons including an AR-15 military-style rifle, a 12-gauge shotgun and a .40-caliber pistol.
His one-bedroom apartment was later found to be booby-trapped with an array of home-made explosive devices, which police had to disarm before entering the dwelling.