>>> confrontation between a group of bikers and the driver of a suv. two more of the bikers are now in custody was we learned more about how some of those riding in the kbrup were apparently police officers themselves.

>> reporter: it is possibly the most dramatic moment in a video that has now been viewed by millions. a biker takes off his helmet, rushes the linde 's suv and smashes the driver's side window. today the motorcyclist in the video was arrested and charged with gang assault in the first degree. another biker was charge and his lawyer says he's kroop rating with authorities. while the nypd continues to investigate, the department itself is under scrutiny. as many as six unauthorized officers may have taken part in the unauthorized bike rally. police sforss say this man was so undercover he didn't want to step in. internal affairs is investigating why it took four days for him to come forward. this man was there and he said he saw one of the bikers go for linde 's wife.

>> with his two hands real hard pulling her out. that's when everybody started screaming, a lot of womens, no, not the lady, not the baby. no, she has a baby.

>> reporter: the crowd stopped them from hurting the mother and baby.

>> the man was knocked down. he was on the floor. he was getting beat up with -- with the --

>> he was smashing his head with a helmet?

>> yes. many times.

>> reporter: he jumped in between linde and the bikers.

>> can you explain how angry these guys were at the moment?

>> real angry. they were acting like savages.

>> reporter: this afternoon he was honored for stepping in. police sforss tell nbc news that they are still poring over video. nbc news new york.