'Not my president'- Protests in California after Donald Trump wins US election

San Francisco: Protests erupted in the US state of California after Donald Trump was declared the winner of the presidential polls with some demonstrators shouting "not my president".

Protesters gathered in Oakland and sought to block freeways and create a commotion.

The protesters forced Bay Area Rapid Transit (BART) to shut down and at least one demonstrator was struck by a vehicle, KTVU-TV reported.

The 20-year-old woman was among 200 protesters who surged onto Highway 24 at the border of Oakland and Berkeley when she was struck by a car.

The California Highway Patrol (CHP) momentarily shut down the highway as they tended to the woman, who was rushed to an area hospital with what Sgt. Matt Langford described as "major injuries".

The CHP moved the protesters off the freeway and they dispersed throughout the area, the SF Gate reported.

It was also reported that some cars were set on fire and other vehicles had broken windows.

KTVU said that Trump supporters hosted a watch party at the Twitter headquarters in San Francisco and some protesters were seen in masks.

Protesters were also seen in Berkeley, chanting "not my president."

It was a heart-break for Democratic nominee Hillary Clinton, who was hoping to become the first woman president of the US, as the 70-year-old business tycoon edged past her in a see-saw battle.

The election saw the ugliest campaign in US history with Clinton and Trump trading personal attacks and allegations. Violence also hit Trump's rallies many times during the course of the campaign.