Five Santa Ana police officers took the stand, for the first time detailing accounts from witnesses who saw the fight last month.
Officer Roland Andrade said one witness told him someone from Zavala and Brito's group bumped into Pham, setting off an argument.
Andrade was told one of the women told Pham, "Excuse me," using a sarcastic tone. That prompted Pham to start screaming obscenities at the group. The witness said Pham had to be restrained by her friends.
Zavala and Brito's group walked away, but then came back twice to confront Pham, 23, who broke free from her friends and threw the first punch, Andrade said the witness told him.
Pham was kicked in the head by a woman after tumbling to the ground in the scrum, the officer said.
Hospital tests revealed there were no traces of drugs in Pham's system, but Andrade said alcohol was detected, though he didn't know her blood-alcohol level.
Senior Deputy Dist. Atty. Troy Pino played a video shot on a cellphone of the incident and asked Santa Ana homicide Det. Leo Rodriguez to identify those involved in the fight.
He first identified Zavala, who appeared to be stooping over and reaching for something on the ground with her right hand. Seconds later, the video shows a woman wearing black pants, a black shirt and a blue sweater launching what investigators believe was the first punch in the altercation.
"That is victim Pham," Rodriguez said.
Brito is singled out moments later, talking to a security guard who had pulled her aside. She is then seen walking around the fight, which spilled onto the ground, and making a kicking motion toward the sidewalk.
The case drew widespread attention because videos of the melee appeared to show other club patrons standing around watching or filming the attack rather than intervening. The incident also led city officials to reassure the public the revived downtown scene was safe.
Prosecutors, however, said that as many as 15 people tried to come to Pham's aid.
The officers' testimony came during a preliminary hearing to determine whether there was enough evidence to order the women to stand trial in the death of Pham, an aspiring journalist who was out with friends when violence erupted outside a popular restaurant and lounge.
The hearing at the Westminster Justice Center is set to continue Tuesday.