Lanes of the 101 Freeway in Hollywood were blocked by a truck aboard which several occupants were playing loud music and singing, according to witnesses.

The southbound 101 was jammed for several miles due to the incident, which some witnesses said appeared to be some type of intentional act or protest. Only one of the southbound lanes was open as of 10:50 a.m.

Sarah Faden, a spokeswoman for the Los Angeles Police Department, said three individuals were playing music and "creating some type of havoc" on the freeway between Sunset Boulevard and Alvarado Street.

"We have reports that someone got on top of his cab and began to sing," said Francisco Villalobos of the California Highway Patrol.

One witness told The Times that the people on the truck appear to be performing some type of concert.

[Updated at 11 a.m.: The people blocking the freeway appear to be members of a band called Imperial Stars. The group has a song called "Traffic Jam 101."

Members of the group were being arrested, officials said.]

-- Richard Winton and Andrew Blankstein

Photo: The scene on the southbound 101 Freeway in Hollywood. Credit: KTLA. Watch video here.