Angry protesters in California some vandalizing, looting and clashing with police, gathered for a second night Monday to condemn recent killings of black suspects by white officers.

Hundreds of protesters gathered late Sunday and continued marching into early Monday in the cities of Berkeley and Oakland, according to police in the western US state.

Some smashed store windows and looted shops and a fire was set in a residential street in Berkeley. The marchers also blocked a major highway as they moved to the neighbouring city of Oakland amid a heavy police presence.

Berkeley police said some of the approximately 600 protesters lobbed bottles and overturned trash cans, which they also set ablaze.

Berkeley police spokeswoman Jennifer Coats said there had been five arrests and that two officers had been injured.

Police also reported that at least one person was assaulted while trying to stop a demonstrator from looting a shop.

But many protesters marched peacefully, some carrying signs reading “Jail killer cops” and “Police brutality and murder must stop” as they marched through the streets and staged so-called die-ins by lying on the ground.

Demonstrations had also turned violent the night before in Berkeley, where police used tear gas after clashing with crowds who threw projectiles, looted shops and vandalized cars. Officials said several officers were injured.

Meanwhile, hundreds gathered in New York for a fifth night of demonstrations, clogging downtown stores and a central transport terminal.

President Barack Obama urged the country’s youth to be patient in the fight against racism, and said reversing the problem will take time.

“This isn’t going to be solved overnight, this is something that is deeply rooted in our society, it’s deeply rooted in our history,” he said in an interview with Black Entertainment Television to be aired Monday night.

“We have to be persistent, because typically progress is in steps, it’s in increments.”

Demonstrations have erupted across the United States over the past two weeks, sparked by a grand jury decision not to indict a police officer in Ferguson, Missouri after he shot dead an unarmed black teenager in August. The officer said he was acting in self-defence after being assaulted.

Protests were bolstered by other killings by police, including the July choking death of Eric Garner in New York by a white police officer who wrestled the black 43-year-old father of six to the ground for allegedly selling untaxed cigarettes.

The white officer involved in that case was also cleared by a grand jury last week, provoking a fresh wave of demonstrations in several US cities.

In another case, Akai Gurley, 28, was shot dead by a police officer on November 20 in a dimly lit staircase at a New York apartment building while he was with his girlfriend. A grand jury was also expected to decide whether that case should go to trial.

High profile sports stars joined the condemnation over the weekend against the recent killings, with several American football and basketball players wearing T-shirts bearing the phrase “I can’t breathe,” which were the last words uttered by Garner as he was held in a chokehold.