Pro-Palestinian demonstrators blocked San Francisco's Golden Gate Bridge on Monday, completely halting traffic for hours as part of a coordinated day of action against Israel's war in Gaza. 

 Aerial footage Monday morning showed stationary traffic in one direction on the iconic bridge, while lanes in the other direction were empty, with police present.

Similar protests were held across the United States and around the world, after the group A15 Action called for coordinating a "multi-city blockade... in solidarity with Palestine."

"In each city, we will identify and blockade major choke points in the economy, focusing on points of production and circulation with the aim of causing the most economic impact," the group said on its website.

Protesters blocked roads Monday in Philadelphia and shut down highway traffic heading into Chicago's O'Hare International Airport -- forcing some passengers to make their way by foot to catch their flights.

Protests were also planned in Canada, Italy, South Korea, Colombia and Belgium, while the X account for A15 posted photos of demonstrations in Greece, Spain and Australia.

Demonstrators who were blocking traffic on the Golden Gate Bridge held a banner reading "Stop the world for Gaza."

"We know that money is really what speaks to (elected leaders)," an organizer, who gave her name as Hayshawiya, told the San Francisco Chronicle from the bridge, adding they would stay until the police forced them out.

The California Highway Patrol said on X that officers were making arrests before announcing that traffic had reopened in both directions just before 12:30 pm (1930 GMT).

- Biden faces pressure -

Monday's protests come as US President Joe Biden faces continued criticism from within his own party about Washington's continued support of Israel.

Israel launched its punishing offensive in Gaza last October after an unprecedented attack by Hamas militants resulted in the deaths of 1,170 people, mostly civilians, according to Israeli figures.

At least 33,797 people have since been killed in Gaza, mostly women and children, according to the health ministry in the Hamas-run territory.

The growing death toll has unnerved both voters and some elected officials, including Biden ally Senator Chris Coons, who called on conditioning US aid to Israel after a strike killed seven aid workers from an American charity operating in Gaza.

As the country heads toward elections in November, Biden will have to juggle the discontent among Democrats with those in the party who support Israel, all while battling Republican nominee Donald Trump.

In another protest, in Los Angeles, a few hundred people marched downtown behind a banner reading "End the siege on Gaza now, end US funding to Israel."

The demonstrations came on the same day as the US tax deadline, protesters in Philadelphia noted.

"We believe we should be funding things that support the people of Philadelphia... things that will actually make our city safer," organizer Hannah Zellman told the Philadelphia Inquirer.

Other protests in the United States were held in Connecticut, where demonstrators blocked access to an aerospace manufacturer, and in Oregon, where a highway was shut down.

In New York, protesters took to the Brooklyn Bridge and temporarily halted traffic before police stepped in to make arrests and clear the roadway.