A woman was egged and a man was left bleeding after he was struck in the head. Police arrested four people at the event that also saw numerous fights between protesters and Trump supporters.

Violence erupted Thursday evening in San Jose outside a rally for Republican presidential candidate Donald Trump. Protesters and police are getting a little scrappy

In the hours leading up to Trump's speech, protesters and Trump supporters verbally sparred in the street outside the San Jose convention center. But while heated, those exchanges remained relatively civil. As protesters' ranks swelled from a few dozen to several hundred, they became increasingly hostile, jeering Trump supporters trickling into the event behind a wall of police. But it wasn't until supporters began leaving the rally that things turned ugly. Trump backers, safe behind the police, tossed taunts back at the raucous protesters, unaware that the line of officers ended only a few yards away — leaving them directly exposed.

Video from the scene showed a self-identified Trump supporter being struck in the head by a protester. He later had blood streaming down his face. View this video on YouTube youtube.com

Another Trump supporter was attacked with eggs and bottles. Noah Berger / AP

Among the supporters taunting the protesters was the woman who would eventually be cornered by the angry mob. Pinned against the doors of the Marriott hotel next to the convention center, she became the focal point of the crowd's anger. Protesters hurled obscenities, spit on her, and ultimately began egging her. Although hotel staff eventually rescued her, police never stepped in — a decision that clearly emboldened protesters, who took to the streets, marching, burning flags, and chanting "Fuck Trump!"

Watch: The moment a Trump supporter, surrounded by protesters, is egged in the face, hit by other food.

Protesters cornering Trump supporters as they leave. This woman taunted them. They cornered her & threw eggs at her

Another protester was seen punching a man in the head as he walked down a street. I called 911 but no one answered. Donald trump protest in San Jose, CA

Other images from the scene showed fights breaking out between Trump supporters and protesters. Within minutes of the rally's end, the bulk of the crowd spilled into the streets of downtown San Jose, mixing in with protesters and creating a volatile situation. Fights between Trump supporters and protesters began to break out almost immediately. In at least two instances Trump supporters engaged with protesters, chanting "Donald Trump" and walking directly into the thickest, angriest portions of the protests. But things quickly spiraled, and rallygoers simply trying to get back to their cars were chased down and beaten — often at the feet of San Jose Police, who stood by motionless.

Raw video: Fighting continues in streets following @realDonaldTrump rally in San Jose.

Big fight breaks out

Some protesters were seen burning an American flag. Protests have moved out onto San Carlos st

At least one protester, who was wearing a "Make America Great Again" hat he had stolen from a rally participant, was attacked by protesters, who mistook him for a Trump supporter.

Police were present at the gathering, but took a hands-off approach to the crowd. In some cases, officers stood nearby as fighting and violence broke out. Cops standing by as a trump supporter is chased by protesters

A police source told BuzzFeed News that officers were under orders to not break ranks, and that while "nobody wants to see somebody beaten... we had a global plan." The source added that the department did not want officers to step in for several reasons, notably out of fear for individual officers' safety, as well as concerns that breaking up a fight may end up escalating the violence.

Eventually police declared an unlawful assembly, and began pushing protesters back. Police are pushing protesters back now

Fights between cops and protesters starting

About two hours after the gathering turned violent, police were making arrests. Cops are making arrests in San Jose

Campaign officials for Hillary Clinton and Bernie Sanders condemned the violence. Noah Berger / AP

John Podesta, chairman of the Hillary Clinton presidential campaign, tweeted that "violence against supporters of any candidate has no place in this election." Sanders' rapid response director tweeted that "we cannot stop Trump's violent rhetoric with violence — only peaceful protest in a voting booth can do that."