Guzman still has four bullets in his body.
Guzman then took the district attorneys to the night that Bell was killed back on November 25, 2006, the day Bell was to be married.
Guzman identified defendant Gescard Isnora on Tuesday as the initial shooter.
"This dude is shooting like he's crazy, like he's out of his mind," Guzman said.
He painted the picture of an upbeat bachelor party that turned suddenly violent when everyone was leaving for the night.
Bell was driving away from his night out with the boys at Queens club, Kalua. Guzman and Trent Benefield were with Bell when he hit a minivan and suddenly, according to Guzman's testimony, "a black man with a silver gun" starting shooting at them.
Guzman said that man never identified himself as a police officer. When the shooting started, Guzman said everything slowed down. He then recalled saying to Sean Bell, "This is not robbery, they are here to kill us."
Guzman recalled locking eyes with Isnora, whom he repeatedly referred to as "that kid" or "dude." Around the same time, he said, an unmarked police van collided with a car driven by Bell as shots rang out.
"That's all there was - gunfire," he said. "There wasn't nothing else."
Guzman said the gunfire was continuous. He said Bell put the car in reverse, backed up and hit something else. At one point, Guzman says, he spoke to Sean Bell and said, "S, I love you, son." He says Bell said, "I love you too." Then Guzman says Bell "stopped moving."
Posecutors asked Guzman about his criminal record. He has two felony convictions, including one for selling drugs. He served about two years behind bars.
Prosecutors have portrayed Isnora and two other detectives, Michael Oliver and Marc Cooper, as reckless cowboys who were poorly prepared for an undercover operation targeting prostitution at the strip club where Bell was hosting a bachelor party.
Isnora and Oliver have pleaded not guilty to manslaughter. Cooper has pleaded not guilty to reckless endangerment.
The detectives, wearing street clothes and trying to blend in with club patrons, say they became alarmed after witnessing an argument outside the club between a belligerent Bell and the driver of an SUV who appeared to be armed, then overheard Guzman say to someone, "Yo, go get my gun."
Isnora, who tailed Bell, Guzman and Benefield on foot, confronted the men as they headed for their car, suspecting they might be retrieving a weapon.
He told a grand jury he identified himself as a police officer and was the first to open fire after Guzman made a sudden move and Bell bumped him with his car while frantically trying to pull away.
On Tuesday, Guzman said he too believed the SUV driver was armed because the man put his hand in his right coat pocket and told Bell's group, "I don't fight no more."
But Guzman also said he played the role of peacemaker outside the club, telling the SUV driver no one wanted trouble. He also denied saying anything about having a gun because he didn't have one that night.
"Where I'm from, that's not a good bluff," he said, raising his voice in one of several heated exchanges with defense attorney Anthony Ricco. "I don't know where you come from."
He later mocked Ricco for questioning his claim that Bell's car never bumped Isnora, saying, "It's not rocket science, man."
Ricco suggested that Guzman's combative demeanor on the stand was "exactly what was going on in front of that club."
The first of Bell's friends, Trent Benefield, took the stand on Monday. But he may have damaged his own credibility, and the prosecution's case, after he appeared to contradict himself and admitted to daily marijuana use.
