At least 21 people were arrested after opponents of President Donald Trump and supporters clashed at a march in Berkeley, California.

Several people were injured when fighting broke out on a day of nationwide marches calling on the president to release his tax returns.

US media said hundreds of people gathered at a park, including Trump supporters who held a free speech rally, while opponents of the president’s policies shouted and chanted. Several fights broke out.

The Los Angeles times reported that 21 people were taken into custody.

Supporters held signs in support of “Free Speech.”

Protests have been taking place in more than 150 locations across the United States to call on President Trump to release his tax returns.

Trump broke a long-held tradition by not releasing his paperwork during his Presidential campaign.

His critics want to know who he has been dealing with and if there are any conflicts of interest.

There is no law requiring presidents to release their tax returns, but Donald Trump has found himself under public pressure and some information from a 2005 tax return was leaked to the media last month.

The protests were timed to coincide with the traditional Mid-April deadline for Americans to file their tax returns.