Pretoria - Paralympian Oscar Pistorius failed to take steps to avoid the death of his girlfriend Reeva Steenkamp, Judge Thokozile Masipa said in the North Gauteng High Court in Pretoria on Thursday.
"He failed to take any steps to avoid the resulted death," she said, reading out her judgment.
"I am of the view that the accused acted too hastily and used excessive force. In the circumstances it is clear that his conduct was negligent."
Masipa adjourned the judgment to Friday at 09:30.
Earlier, there was an short delay in the start of proceedings after the lunch break.
Pistorius's lawyer Barry Roux and prosecutor Gerrie Nel were seen leaving the courtroom and disappearing through the door to the judge's chambers.
Court resumed about 15 minutes later, but Masipa only spoke for several minutes more on negligence before she abruptly adjourned proceedings.
Steenkamp was shot in Pistorius's Pretoria home on 14 February last year.
During the trial Pistorius has said he thought an intruder was behind the door of the toilet in his Pretoria home when he shot through it. He fired four times, killing Steenkamp.
After the adjournment, Steenkamp's friend Marc Batchelor stood with her Johannesburg "family" the Myers and said how upset he was with how the judgment was going.
Steenkamp's friend Gina Myers was crying after lunch and was consoled by her family.
Earlier, Steenkamp's parents June and Barry sat straight, looking at Masipa as she spoke.
They left as soon as court was adjourned, flanked by their lawyer Dup du Bryun.
Pistorius left through the door used by Masipa while his family trickled out the main entrance.
During her judgment, Masipa said various questions had to be taken into consideration, including if a reasonable person would have foreseen the possibility that someone might be struck when Pistorius shot and someone could die.
She said it should also be taken into consideration if a reasonable person would have taken steps to guard against the possibility of killing another person.
She said in Pistorius's case the answer to both is yes.
The State had argued that Steenkamp's killing was premeditated.
However, on Thursday Masipa said there was not enough evidence for premeditated murder.
Masipa was still due to rule on whether Pistorius was guilty of culpable homicide, which is defined as the unlawful killing of a person without an intention to kill.
Pistorius is also charged with three contraventions of the Firearms Control Act - one of illegal possession of ammunition and two of discharging a firearm in public.