Demonstrators flooded a highway in Oakland, California, prompting a heated standoff in the freeway between protesters and California Highway Patrol.

Some threw explosives, bottles and rocks at officers, authorities said.

Officers responded by deploying gas and arresting eight protesters.

Gurpreet Heer, a student at the nearby University of California at Berkeley, said he saw people throwing glass and rocks at police.

“People were vandalizing police cars and jumping on the cars,” Heer said.

Police said five patrol cars had been damaged.

In the city of Berkeley, some protesters looted and vandalized businesses late Sunday night, police spokeswoman Jennifer Coats said.

One protester was struck in the head with hammer when he attempted to keep fellow protesters from damaging and looting a Radio Shack, Coats said. The man was hospitalized, but his injuries are not believed to be life-threatening.

Coats said some arrests were made, but could not confirm the number of arrests.

The acts of violence were apparent anomalies in a sea of protests nationwide decrying a grand jury’s decision not to indict the officer who killed Garner, an unarmed black man.

Garner’s last words — “I can’t breathe” — have become a protest chant.

Caroling their grievances

Some demonstrators are getting more creative.

In New York, protesters at Penn Station sang “justice carols,” such as these lyrics to the tune of “Little Drummer Boy”:

“Help, he told them,

pa rum pum pum pum,

I cannot breathe, you see,

pa rum pum pum pum,

Our city’s finest bring,

pa rum pum pum pum,

Death to this human being.”

Hundreds of protesters also gathered at Grand Central station and Macy’s in Herald Square — sites of multiple “die-ins” over the past few days — before barging through the nearby Toys R Us to lie on the floor en masse.

One young couple made the event a family affair, lying on the floor with their toddler between them.