Testifying in a Manhattan courtroom yesterday, three passengers described in harrowing detail the terror, chaos and shock when a van carrying 15 Hasidic students across the Brooklyn Bridge came under gunfire in March.

The students were returning to Brooklyn from a Manhattan hospital where their religious leader, the late Lubavitcher Rebbe, Menachem Schneerson, had just undergone successful eye surgery. But in what the prosecution says was a sudden and unprovoked burst of gunfire, their joy and relief turned into a nightmare, as the windows in the van were shattered and a rain of bullets smashed through it, killing one student and wounding three others.

The defense does not dispute that the man accused in the case, a 28-year-old Lebanese immigrant named Rashid Baz, fired the shots, but is offering an insanity defense based on the contention that Mr. Baz suffers from the shock of growing up in war-torn Beirut.

According to the testimony yesterday in State Supreme Court in Manhattan, Aaron Halberstam, a 19-year-old student who was shot dead in the attack, was never meant to be in the van returning from the hospital. One of the passengers, Shimon Kramer, testified, "At the last minute, Ari knocked on the van door looking for a ride as we were leaving and we let him in."

As he recalled how Mr. Halberstam came within seconds of missing the van, the victim's mother, Devorah, who was in the courtroom, choked up with tears.

A second passenger, Yaakov Reiter, 18, said the first thing he heard as the van was coming onto the bridge was a series of loud bangs.

"How many?" asked William Mahoney, an assistant district attorney. "One, two, many?"

"Lots of them. At first I didn't know what they were — backfires or some kind of explosions."

"What did everyone do?"

"Someone screamed, 'Arabs are shooting at us.' So I got down on the floor and knelt there. And then the shooting stopped for a moment and the van started to go forward with a bunch of bumps," he said.

"But then there were more shots and people were screaming — 'He's still firing at us!' — and there were more shots and people shouting 'Stop, stop,' or yelling to crash the van to a stop."

Wearing a dark, double-breasted suit and testifying in a clear voice, Mr. Reiter said Sholom Wilheim, the driver of the van, had the composure to shout to the others aboard: "Get the plate number, remember the plate number."

The third passenger to testify, Mendel Krinsky, said he took out paper to write down the number they were shouting but, in the chaos of the attack, forgot to write it down.

After a third series of shots ended, Mr. Reiter said the van stopped on the Brooklyn end of the bridge where he noticed that one of the students sitting behind him had been wounded.

"He was lying on the floor with his back up and he was still moving his arms," he said. "Blood was coming out of him and I put my hand on his head to stop the bleeding."

Mr. Baz admitted to the police that he fired on the van, but he said it was only after he had got into an argument with the van's driver and only after the driver had pulled a gun on him. His lawyer said he was not responsible for the shooting because he suffered from a post-traumatic shock shared by many Arab victims of Middle East conflict.

Mr. Mahoney asked Mr. Reiter if anyone in the van had any conversation with anyone outside as the van came on the bridge, as Mr. Baz told the police.

"No."

"Did anyone have any words or make any motion to someone outside?"

"No."

"Did the driver, Sholom Wilheim, take out a gun?"

"No."

"Point a gun?"

"No."

"Have a gun?"

"No."

Mr. Baz is charged with murder and assault in the attack and, in the second day of testimony, he was identified in court for the first time as the man who fired at the van from a blue Chevrolet.

Gershon Kaufman, who said he was driving behind Mr. Baz and the van on the bridge, was asked if he could identify the car's driver.

"I think so," he replied.

"Look around the courtroom," said Mr. Mahoney, as Mr. Baz's lawyer, Eric M. Sears, rose and shouted, "Objection."

"Overruled," said Acting Justice Harold M. Rothwax.

After peering for a moment at the defense table, Mr. Kaufman said: "Yes, I see the person," and pointed at Mr. Baz.