Protesters Clash with Cops at California Trump Rally

At least one police car was smashed up as hundreds of demonstrators – many of them waving Mexican flags – took to the streets outside the Pacific Amphitheater in Costa Mesa, Orange County where Trump was speaking.

The protesters flooded the street outside the amphitheater with some stomping on cars, hurling rocks at motorists and forcefully declaring their opposition to Trump - bringing traffic to a halt and creating a tense standoff with authorities, Daily Mail reported.

One Trump supporter was pictured with a bloody face after clashing with the anti-Trump activists, many of whom appeared to be young Hispanic people.

The violence in Southern California where Latinos make up a large segment of the population suggests Trump may face more of this in the days to come, as he campaigns ahead of the state’s June 7 primary. Trump currently leads Kasich and Cruz in the California polls, with an estimated 45.7 per cent of voters, according to Real Clear Politics.

At one point, a demonstrator was seen stomping on a police car, causing the car's windows to smash, while another scrawled an expletive and Trump's name onto a police cruiser. Some of the protesters also reportedly tossed rocks and debris at cars passing by.

Officers in riot gear from the Costa Mesa Police Department and sheriffs on horseback lined a roadway and told demonstrators to clear the road, but many remained in the street.

Some women also were protesting Trump's lack of engagement on issues of gender equality and women's rights and had slogans such as 'Dump Trump' and 'Gender Equality'.

During his speech, Trump - apparently unaware of the chaos engulfing the rally outside the theater - told the crowd: 'Our rallies are the safest place to be on Earth, believe me.'

Additional forces from law enforcement agencies had been deployed to deal with crowd.

While Costa Mesa officials had also set up an emergency operations center opposite the fairground and amphitheater, with city spokesman Tony Dodero adding earlier, 'we're prepared for the worst.'

There were were nearly 200 officers and deputies at the scene, according to the Orange County Sheriff's Department.

However, as the chaotic scenes played out it seemed police were dealing with a larger and more boisterous crowd than expected.

'It definitely got out of control,' Megan Iyall, 20, who was visiting from Seattle said. 'I shouldn't feel this unsafe.'

She added: 'I know people are angry and upset but that should not be happening.'

The Republican presidential frontrunner was campaigning on Thursday ahead of the state's June 7 presidential primary, among the last in the nation.

He is vying for votes in the primary election in hopes of narrowing the gap to the 1,237 delegates needed to secure the Republican presidential nomination, before the Republican National Convention this summer.

If he doesn't reach that number by then, the convention will be brokered, with delegates making a second vote at the convention to determine the nominee.