President Barack Obama ordered sanctions Tuesday against five people tied to sectarian violence in the Central African Republic and cleared the way for further penalties, stepping up the U.S. response to a crisis that's plunged the former French colony into fear and chaos.

In an executive order, Obama declared a national emergency and said a breakdown of law and order, widespread atrocities and forced use of child soldiers threatens security in the Central African Republic as well as in neighboring nations.

The U.S. sanctions target members of both the Muslim Seleka and the Christian anti-Balaka groups — two sides of a brutal conflict that has confounded the international community.

The sanctions send "a powerful message that impunity will not be tolerated and that those who threaten the stability of the CAR will face consequences," White House press secretary Jay Carney said in a statement.

Word of the U.S. penalties came the same day France's presidency announced that a 26-year-old French photojournalist who had spent months documenting the deadly conflict was killed after being caught in fighting. A freelance photographer, Camille Lepage, had published work in The New York Times and The Wall Street Journal.

The landlocked Central African Republic exploded into sectarian violence in December, but the conflict dates back to March 2013, when an alliance of Muslim rebel groups known as the Seleka overthrew the country's president, Francois Bozize. They quickly became despised by Christians in the capital after Muslim fighters went on looting sprees, raping and killing civilians at random. An armed Christian movement known as the anti-Balaka, aided by Bozize loyalists, began retaliating several months later, sparking sectarian bloodshed.

Seleka was forced from power in January, a transitional government has been established, and about 2,000 French troops and nearly 5,000 African peacekeepers are trying to stabilize the country, which is about the size of Texas. But the violence continues and tens of thousands of Muslims have fled to the north or to neighboring countries in what the United Nations has described as "ethnic cleansing."

Three of the individuals sanctioned by the U.S. on Tuesday, including Bozize, were previously designated for sanctions by the U.N. following a Security Council resolution adopted in January. Obama's executive order also opens the door for the U.S. to sanction additional individuals in the future.

About 1 million people in the Central African Republic have been displaced, the White House said, arguing that attacks perpetrated by both Christians and Muslims have fueled "a crisis of disastrous proportions." The White House said more than 2.5 million people — or more than half the country's population — need humanitarian help.

The individuals sanctioned Tuesday are:

— Bozize, who is accused of supporting anti-Balaka militiamen working to return Bozize to power, and calling on his militia to commit atrocities against the current transitional government and the Islamists.

— Michel Djotodia, the Seleka leader who left power in January under immense international pressure.

— Noureddine Adam, the nation's former public security minister and a Seleka figure, implicated by human rights groups in attacks on dozens of villages.

— Abdoulaye Miskine, described by the White House as the leader of an ex-Seleka group called the Democratic Front of the Central African Republic People.

— Levy Yakete, an anti-Balaka political coordinator.