University of California, Berkeley has cancelled an event that was set to feature the right-wing writer Milo Yiannopoulos after a protest turned violent.
The controversial Breitbart senior editor - who was permanently banned from Twitter last year - was due to speak after being invited by College Republicans.
Around 1,500 protesters had gathered to protest the appearance yesterday evening, but according to Berkeley News violence broke out when 150 "masked agitators" interrupted the otherwise peaceful protest.
A number of fires were started, while fireworks were reported to have been thrown at windows and police officers.
Yiannopoulos was evacuated from the campus as a result of the protests, and campus buildings were locked down.
.@UCBerkeley Milo event cancelled. Shelter in place if on campus. All campus buildings on lockdown. #miloatcal
— UC Police, Berkeley (@UCPD_Cal) February 2, 2017
Campus officials said they condemned "in the strongest possible terms" the violence, and regretted that it overshadowed the non-violent protest efforts.
In a statement on Facebook, Yiannopoulos said: "My team and I are safe. But the event has been cancelled. I'll let you know more when the facts become clear. One thing we do know for sure: the Left is absolutely terrified of free speech and will do literally anything to shut it down."
The visit had already been a source of controversy, with many activists calling for the self-proclaimed internet troll to be banned from visiting the campus.
In a statement last week, Berkeley Chancellor Nicholas Dirks said Yiannopoulos is a "troll and provocateur who uses odious behavior in part to 'entertain,' but also to deflect any serious engagement with ideas".
"He has been widely and rightly condemned for engaging in hate speech directed at a wide range of groups and individuals, as well as for disparaging and ridiculing individual audience members, particularly members of the LGBTQ community," he added.
However the chancellor said the event would go ahead as "the university cannot censor or prohibit events" - although he warned of the planned protest and stressed that groups on campus have a "moral responsibility for the consequences of their words, actions, events and invitations".
President Donald Trump commented on events on Thursday morning, appearing to threaten Berkeley with the removal of federal funding.
If U.C. Berkeley does not allow free speech and practices violence on innocent people with a different point of view - NO FEDERAL FUNDS?
— Donald J. Trump (@realDonaldTrump) February 2, 2017