Black clad youths smashed windows at anti-Trump protest.

As Trump, his supporters, former presidents and other dignitaries gathered on the National Mall for the swearing-in ceremony, opponents marched in nearby streets and were confronted by a heavy police presence.

Most of the noisy protests – including those by an array of anti-racist, feminist, pro-immigration, anti-war and marijuana legalization groups – were peaceful.

Black clad youths smashed windows.

But in at least one incident, black clad youths emerged from the crowds to smash windows in a bank and fast food outlet and throw stones, as riot police deployed pepper spray.

Marchers chanted: “No deportation, no KKK, no fascist USA!”

A 27-year-old financial worker from Tampa Bay in Florida, who did not want to give his name for fear of retaliation by his employer, said Trump’s election victory had left him fearful.

“There is nothing to hope for except for grassroots efforts to oppose him,” he told AFP.

Public interest lawyer Renee Steinhagen, 61, came down from New York to protest against Trump’s inauguration.

“I’m doing this to express resistance to the change that await us,” she said.

“This administration seems more extreme than any other. This is a simple act of resistance. It’s better than staying at home.”