So much blood the theater floor had become slippery. Bodies with horrific injuries. The eerie sound of cell phones ringing, over and over again.

This is the scene Aurora police Officer Justin Grizzle said he encountered moments after entering the theater where, according to authorities, 25-year-old James Holmes killed 12 people in a July 20 shooting rampage.

Grizzle testified Monday on the opening day of the preliminary hearing for Holmes, who is charged with 166 counts of murder, attempted murder and weapons charges.

The 13-year veteran wiped away tears while describing his efforts to rush badly wounded victims to the hospital in his police cruiser, including shooting victim Ashley Moser and her husband, who wanted Grizzle to turn around and head back to the theater.

"He was shot in the head somewhere. He kept asking where his ... daughter was," Grizzle said. "He opened the door and tried to jump out."

Grizzle said he had to drive and hold the man by his shoulder to keep him in the car.

The girl the man was seeking, 6-year-old Veronica Moser-Sullivan, was shot four times and was among those killed in the shooting at a midnight showing of "Batman: The Dark Knight Rises." Veronica's mother, Ashley, faces a long recovery after being paralyzed in her lower half and miscarrying after the shooting.

The scene was still gruesome when Detective Matthew Ingui arrived 12 hours later with other investigators.

"We saw the first victim laying on the ground," he said "There's shoes, blood, body tissue and popcorn on the floor."

Blood was everywhere, he said.

Ingui described how he outlined each of the victims and marked where the bodies were found. Holmes had no visible reaction during the testimony.

The detective said investigators found 209 live rounds of .223 ammunition and 15 cartridges of .40-caliber rounds inside the auditorium.

The preliminary hearing that began Monday is designed to show a judge that the state has enough evidence to proceed to trial. Prosecutors are calling scores of witnesses and outlining their evidence in the case. The hearing could go on for days.

A gag order imposed by the judge in the case has limited the flow of information about the attack. However, a source said Holmes allegedly went out a rear exit door, propped it open and gathered his weapons. He then returned to the theater and tossed a canister inside before opening fire, the source said.

Screaming moviegoers scrambled to escape from the gunman, who shot at random as he walked up the theater's steps, according to witnesses.

It was a scene "straight out of a horror film," said Chris Ramos, who was inside the theater.

While none of the four law enforcement witnesses who testified Monday offered insight into a possible motive for the shooting, some new details emerged.

Prosecutors showed surveillance camera video taken inside the theater complex that they said shows Holmes -- dressed in dark trousers, a light-colored shirt with a T-shirt underneath and a ski cap covering his hair -- using a cell phone at a ticket kiosk. Holmes printed out a ticket that had been purchased July 8, they said.

The cameras also captured the aftermath of the shooting as waves of people ran out of doors with theater staff behind counters. One employee even leaped over a counter.

There was no video from inside the auditorium where the shootings occurred.

Police Sgt. Gerald Jonsgaard said Holmes stopped the theater door from locking by using a small piece of plastic commonly used to hold tablecloths onto a picnic table. Jonsgaard also said he spotted a shotgun and a large drum magazine that appeared to be jammed on the floor of the theater.

Holmes' attorneys are expected to argue that their client has "diminished capacity," a term that, according to the Colorado Bar Association, relates to a person's ability or inability "to make adequately considered decisions" regarding his or her legal representation because of "mental impairment or for some other reason."

Several times, on cross-examination, they have asked witnesses about Holmes' demeanor and what he looked like when police found him.

The day's testimony concluded with a detective who interviewed people wounded in the attack and the two coroners who conducted the 12 autopsies.

After the hearing, Arapahoe County District Judge William Sylvester will determine whether there is enough evidence for Holmes to stand trial.