One person has been shot at an anti-Trump demonstration in Portland, police say.

Key points: Multiple shots fired after confrontation between driver and protester

Multiple shots fired after confrontation between driver and protester Demonstrations taking place in Miami, Atlanta, Philadelphia, New York, San Francisco and Portland

Demonstrations taking place in Miami, Atlanta, Philadelphia, New York, San Francisco and Portland In Portland, protesters blocked traffic, threw objects at police dressed in riot gear

"One person down. Everyone needs to leave the area immediately," police said on Twitter after the shooting, adding that it took place as protesters crossed the city's Morrison Bridge.

In a statement, police said the suspected shooter had been in a vehicle on the bridge when there was a confrontation with a protester.

"The suspect got out of the vehicle and fired multiple shots injuring the victim," the statement added.

The victim was treated at the scene before being taken by ambulance to a Portland hospital with non-life-threatening injuries.

The suspect was still at large, police added.

Protests are taking place in several US cities for a fourth straight night since Donald Trump's shock election victory, including in Miami, Atlanta, Philadelphia, New York, San Francisco and Portland.

In downtown Portland, protesters blocked traffic and threw objects at police dressed in riot gear who responded with pepper spray and flash-bang devices.

At one point, police pushed protesters back and appeared to take at least one person into custody, according to footage on a local NBC affiliate.

Protesters in Los Angeles are showing their antipathy for President-elect Trump. ( ABC News: Jason J. Cohn )

'We reject the President-elect'

The protesters were voicing anger at President-elect Donald Trump's inflammatory and often deeply controversial campaign rhetoric about immigrants, Muslims and women.

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Hundreds of protesters marched through the streets of Los Angeles, blocking traffic as they waved signs in opposition of Mr Trump and chanted "We reject the President-elect" and "Whose streets? Our Streets".

Several thousand activists marched through downtown Miami, with a few hundred making their way onto a highway, halting traffic in both directions.

In New York, demonstrators again gathered in Washington Square Park and by Trump Tower, where the Republican President-elect lives, on Fifth Avenue.

Leslie Holmes, who attended the Washington Square Park rally, described herself as an armchair liberal but declared: "I'm not going to be armchair anymore".

"I don't want to live in a country where my friends aren't included, and my friends are fearful, and my children are going to grow up in a world that's frightening, and my granddaughters can look forward to being excluded from jobs and politics and fulfilling their potential, so I'm here for them," she said.

Mr Trump, who initially denounced Americans who protested against his election win, saying they had been "incited" by the media, reversed course and praised them on Friday.

"Love the fact that the small groups of protesters last night have passion for our great country. We will all come together and be proud!" Mr Trump said on Twitter.

Protesters continue to flood the streets of major cities in the US. ( ABC News: David Weber )

Anti-Trump rally scheduled for Inauguration Day

With the country evenly divided, many voters were shocked by the result given that opinion polls failed to predict Mr Trump's triumph.

The Republican Party also managed to maintain its majorities in both houses of Congress in Tuesday's vote.

More anti-Trump demonstrations were planned for the weekend, and a group calling itself #NotMyPresident has scheduled an anti-Trump rally for Washington on January 20, when Mr Trump formally succeeds President Barack Obama.

Republican National Committee Chairman Reince Priebus acknowledged on Friday the tight race with Mrs Clinton, but said anti-Trump protesters had to accept the election results.

He pointed to Mr Trump's call for unity and meetings on Thursday with Mr Obama and Republican leaders as reasons for reassurance.

Mr Trump's base of support in the election was the broad middle of the country, with voters in states that had long supported Democrats shifting to him after he promised to renegotiate trade deals with other countries.

Opinion polls failed to predict Mr Trump's triumph, leaving many voters shocked by the result. ( Reuters: Patrick T Fallon )

AP/Reuters