The White House on Thursday called for Ukrainian President Viktor Yanukovych to remove his security forces from the scene of protests in Kiev -- its most forceful statement to date on the quickly escalating conflict.

At least 50 people were killed Thursday morning after a tentative truce fell apart, according to a human rights official.

White House press secretary Jay Carney said Yanukovych's forces have gone too far.

"We are outraged by the images of Ukrainian security forces firing automatic weapons on their own people," Carney said. "We urge President Yanukovych to immediately withdraw his security forces from downtown Kyiv and to respect the right of peaceful protest, and we urge protesters to express themselves peacefully."

Here's the rest of Carney's statement:

"We urge the Ukrainian military not to get involved in a conflict that can and should be resolved by political means. The use of force will not resolve the crisis -- clear steps must be taken to stop the violence and initiate meaningful dialogue that reduces tension and addresses the grievances of the Ukrainian people.  The United States will work with our European allies to hold those responsible for violence accountable and to help the Ukrainian people get a unified and independent Ukraine back on the path to a better future."