OAKLAND — The partner of the officer charged in an Oakland train station death said Wednesday the shooting happened during a chaotic scene where bystanders were yelling and one threw a cell phone at him.

During the third day of a hearing to determine whether former BART officer Johannes Mehserle will stand trial for murder, Officer Jon Woffinden said the New Year’s Day incident was one of the most frightening he had experienced in his 12 years as an officer.

He said he was “extraordinarily scared,” and testified there could’ve been another 20 to 30 officers on scene because of the tension. Woffinden said people were yelling profanities and one person threw a cell phone at him.

Mehserle’s lawyer said his client didn’t intend to shoot 22-year-old Oscar Grant, who he said was “actively resisting arrest.”

Attorney Michael Rains said Mehserle should not be facing the extraordinary charge of murder.

“This is not a murder because there is no malice. There is no malice because Mr. Mehserle did not intend to shoot Mr. Grant. Mr. Mehserle intended to use his Taser,” Rains said.

Mehserle, 27, a graduate of New Technology High School in Napa and also the Napa Valley College police academy, has pleaded not guilty and is free on bail.

The hearing Wednesday followed two days of testimony from witnesses appearing for the prosecution. Several said the officers acted overly aggressive and many said Mehserle looked surprised and shocked after he pulled the trigger.

Train passenger Alika Rogers testified Wednesday there was a lot of “mouthing off and resisting,” by Grant and his friends. She said she told a detective that she thought a riot was going to break out because of the unrest.

“I remember thinking, ’Oh, I’m going to see someone get Tased,”’ Rogers said.

Woffinden, who did not see the shooting, said he thought the “noise” was a Taser.

“It didn’t sound to me like a loud gunshot,” he testified.

He said he briefly talked to Mehserle after the shooting and said Mehserle’s forehead was sweaty, his face flush and his eyes big. It was clear Mehserle was upset and distraught, Woffinden said.

Officers were called to the Fruitvale station over reports of fighting on the train. They rounded up Grant and his friends against a platform wall and while apparently trying to arrest Grant as he lay face down, Mehserle shot him.

Deputy District Attorney David Stein attempted to discredit Woffinden’s testimony, calling into question his remark about the events being extremely frightening.

“You said this was among the most scariest incidents you have ever been involved in?” Stein asked.

“Yes,” Woffinden said.

“Did you hit your emergency button (for backup)?”

“No,” Woffinden said.

“You never pressed that button?” Stein asked.

“No.” Woffinden said.

Stein later asked Woffinden if he saw something on the platform that justified using lethal force. Rains objected.

The case has enflamed residents, who see the incident as another display of tension between police and the community, especially the black community. Mehserle is white and Grant was black.

Rogers said passengers were shouting about police brutality and invoking the Rodney King incident, when King, who is black, was videotaped being beaten by white Los Angeles police officers after he was stopped for speeding in 1991.

After the hearing, expected to resume Tuesday, Grant family attorney John Burris said Woffinden’s testimony raises credibility issues.

“If you look at the tapes and you see the officer could not identify where the chaos was,” Burris said. “The tapes will clearly show that there was nothing Oscar Grant was doing to justify the use of deadly force or even the Taser as a defense.”