A day after the military announced that April was the deadliest month for U.S. forces in Iraq this year, thousands of anti-war demonstrators marched Saturday through lower Manhattan to demand an immediate withdrawal of troops.

Cindy Sheehan, a vociferous critic of the war whose soldier son also died in Iraq, joined in the march, as did actress Susan Sarandon and the Rev. Jesse Jackson.

"End this war, bring the troops home," read one sign lifted by marchers on the sunny afternoon, three years after the war in Iraq began. The mother of a Marine killed two years ago in Iraq held a picture of her son, born in 1984 and killed 20 years later.

One group marched under the banner "Veterans for Peace."

"We are here today because the war is illegal, immoral and unethical," said the Rev. Al Sharpton.

"We must bring the troops home."

Organizers said the march was also meant to oppose any military action against Iran, which is facing international criticism over its nuclear program. The event was organized by the group United for Peace and Justice.

The march stepped off shortly after noon from Union Square, with the demonstrators heading for a rally between a U.S. courthouse and a federal office building in Lower Manhattan.

The military said Friday that at least 67 U.S. troops have died in Iraq in April.

That figure is well below some of the bloodiest months of the Iraq conflict, but is a sharp increase over March, when 31 were killed. January's death toll was 62 and February's 55. In December, 68 Americans died.