BOSTON – Frank Capizzi seemed incredulous when a prosecutor asked him if anything unusual had happened on March 19, 1973.

“Unusual?!” he said. “A firing squad hit us.” For more than two minutes, about 100 shots hit the car, “and it imploded,” he said.

Capizzi described the shooting Friday to a rapt jury in the racketeering trial of James “Whitey” Bulger, the former leader of the mostly Irish-American Winter Hill Gang, who is accused of playing a role in 19 murders during the 1970s and ’80s.

Capizzi said when the shooting stopped, he realized he had been struck in the head and could feel warm blood running down his neck and excruciating pain in his back.

The driver, Albert Plummer, was killed. Capizzi and another man in the car were wounded.

John Martorano testified this week that Plummer was one of two people killed by mistake as Bulger’s gang tried to kill Al “Indian Al” Notarangeli, a member of a rival gang.

Capizzi said he was shot multiple times and was “embedded” with pellets and glass fragments.

“They took out what they could, which was about 11 slugs,” he said.

Capizzi said he did not see who shot at the car, but said he soon left Boston out of fear.

Shortly after Bulger’s lawyer, J.W. Carney Jr., began to question him, Capizzi invoked his Fifth Amendment right against self-incrimination. Later, after prosecutors and defense lawyers met with the judge, Capizzi took the witness stand again. But Carney said he had no additional questions for the 78-year-old witness.

Prosecutors say Bulger, now 83, was working as an FBI informant providing information on the rival New England Mafia at the same time he was committing a litany of crimes, including murders.

Bulger’s former FBI handler, John Connolly, was convicted of racketeering for tipping off Bulger and his gang about an indictment. After receiving the tip, Bulger fled Boston and was one of the nation’s most wanted fugitives until he was finally captured in Santa Monica, Calif., in 2011.

Bulger’s lawyers deny that he was an informant and say he paid FBI agents to warn him about investigations.

Capizzi was among witnesses prosecutors called Thursday and Friday to show the jury the effects of the carnage they say was caused by Bulger and his gang.

Joseph Angeli, the son of Joseph “Indian Joe” Notarangeli, Al Notarangeli’s brother, recalled suddenly being moved from Massachusetts to California with his mother and siblings in 1973.

“Things were dangerous and my parents thought it best to ship us — my mom and us kids — to a safer place,” he said.

Angeli, who shortened his name, said he found out on his 14th birthday that his father had been killed, allegedly by Bulger’s gang.

Prosecutors on Friday also began the process of introducing Bulger’s FBI informant file to the jury.