Demonstrators rally to end violence in Gaza outside the White House in Washington, Aug. 2, 2014. Image credit: ABC News

WASHINGTON - A pro-Palestinian rally and march on the White House drew thousands today, turning Pennsylvania Avenue and Lafayette Square, the park opposite the White House, into a sea of demonstrators.

Waving Palestinian flags, chanting, "Free free Palestine" and "five, six, seven, eight, Israel is an apartheid state," and holding signs that read "Free Palestine, Let Gaza Live," the demonstrators gathered around a small stage in the park and eventually marched down Pennsylvanian Ave.

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Demonstrators rally to end violence in Gaza outside the White House in Washington, Aug. 2, 2014. Image credit: ABC News

Uniformed Secret Service agents and local police, some on horseback, were on hand.

Protesters criticized Israel's occupation of Palestinian territory and President Obama's assertions that Israel has the "right to defend itself" in the face of Hamas rockets. That defense has meant a string of attacks on Hamas targets in Gaza that have brought criticism even from Obama and Secretary of State John Kerry, who have said Israel should do more to prevent civilian casualties.

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Gaza protest in Lafayette Sq outside White House today pic.twitter.com/k20TlJUHQY — Chris Good (@c_good) August 2, 2014

The rally turned contentious early on, as pro-Palestinian demonstrators and a handful of pro-Israeli protesters, waving a few Israeli flags and holding signs critical of Palestinians and Hamas, confronted each other just feed from the White House lawn.

As the two groups taunted each other, one young pro-Palestinian man erupted in a serious of profanities and had to be restrained by a friend.

READ: Israel Warns Hamas Against Continued Rocket Fire

At one point, police moved metal barriers into place around the pro-Israeli demonstrators and asked pro-Palestinian demonstrators to move back, which they appeared to do without incident.

Pro-Palestinians urged their fellow demonstrators to move away and not focus on the Israel supporters.

The rally was organized by the Answer Coalition, a self-described anti-war and anti-racism group that supports Palestine. The group spread invitations via Facebook, one demonstrator said.

Many protesters held signs depicting casualties of Israel's Gaza offensive, and many were strongly anti Israel.