Mass. Sen. Calls for Answers in Mo. Shooting

U.S. Sen. Elizabeth Warren is calling for answers in Ferguson, Missouri, where police have used tear gas and smoke bombs to repel protesters after the killing of an unarmed teen.

The Massachusetts Democrat tweeted Thursday: "This is America, not a war zone. The people of #Ferguson just want answers. We all want answers."

The demonstrations in Missouri have been sparked by the death of an unarmed teenager who was shot by a police officer. The officer is white and 18-year-old Michael Brown was black.

President Barack Obama said Thursday there is no excuse for the use of excessive force by police in the tense aftermath of Brown's death, and no excuse for violence against the police.

In brief remarks near his vacation spot in Martha's Vineyard, Obama said he wants an open and transparent investigation into the shooting.