An elaborate booby trap system found in the apartment of the suspected gunman in last year's Colorado cinema shooting included improvised napalm and thermite, which burns so hot that water cannot put out the blaze, an FBI bomb technician testified.
Police said loud music playing on a timer-equipped portable stereo was used to lure people to the door.
Prosecutors are trying to show that the shooting in Aurora that killed 12 people and wounded at least 58 was a premeditated act and that James Holmes should stand trial for one of the country's worst mass shootings.
Defence lawyers have said Holmes is mentally ill.
Bearded and dishevelled, Holmes appeared blank as audio from the first emergency call from the cinema was played. The call lasted 27 seconds, and police say at least 30 shots could be heard.
Bomb technician Garrett Gumbinner said three different ignition systems were later found in Holmes's apartment. A thermos full of glycerin leaned over a skillet full of another chemical. Flames and sparks are created when they mix, and a trip wire linked the thermos to the door.
Holmes is charged with more than 160 counts, including murder and attempted murder. Authorities said the victims who died were shot between one to nine times.
Dozens of survivors and family members of the dead have packed the courtroom as details of the attack, until then kept quiet by a judge's order, emerge.
On Monday, police officers struggled to hold back tears during their testimony, describing how they found a six-year-old girl without a pulse, tried to keep a wounded man from jumping out of a moving police car to go back for his young daughter and screaming at a gunshot victim not to die.
Holmes watched intently as one detective showed surveillance video of him calmly entering the cinema lobby, holding the door open for a couple behind him, and printing out tickets to the midnight showing of The Dark Knight Rises.