Students from Northern Ireland who travelled to London to take part in protests against tuition fees have condemned the outbreak of violence.
Trouble flared after a small number of protestors attacked Millbank Tower, where the Conservative party has its headquarters, smashing windows and injuring at least two police officers.
Fiona Kidd from Queen's Student Union took part in the protest.
She said a small number of demonstrators were behind the trouble.
"It's a tragedy that something so special and so momentous has been hijacked and destroyed by a few", she said.
"We just ask people to remember the ethos of the march and that the disruption that's happening wasn't anything to do with the National Union of Students."
Ruth McKee, a Belfast student at Kingston University was covering the demonstration for her student newspaper.
She witnessed the violence as protestors entered the Millbank Tower.
"The cobble stones were ripped up, placards were thrown hard against the glass and at that stage there was a surge from a contingent who turned up at about 2pm who pushed through and were pushing through the glass and into the foyer," she said.
SDLP Youth Member Liam McNulty also took part in the protest. He said the fact that some students had become involved in violence should not overshadow the message to the government.
"Tens of thousands of people marched to demand the sort of higher education system that both David Cameron and Nick Clegg themselves enjoyed but which they are now threatening to deny a new generation," he said.
"That some students took part in civil disobedience in no way detracts from the scale of today's demonstration and their actions pale in significance to the criminal damage the Tories and Liberal Democrats are about to inflict on our universities."