Calling the deaths of 298 passengers aboard a Malaysia Airlines jet shot down by an anti-aircraft missile over Eastern Ukraine an "outrage of unspeakable proportions," President Obama said Friday that while investigators have not  yet determined exactly what happened, it appears as though the missile was fired from an area of Ukraine controlled by Russian separatists.

While Obama cautioned that not all of the facts are known, he said that there are only certain types of antiaircraft missiles that can reach a plane flying at 30,000 feet, the height at which Malaysia Airlines flight 17 was cruising Thursday afternoon when it was shot down. The violence that is taking part in such areas is facilitated in part "by Russian support" for separatists fighting government forces in Ukraine, he said.

Obama did not blame anyone for shooting down the plane, stressing that much investigative work remains to determine what happened. But he had strong words for Russian President Vladimir Putin, who he said could stop the violence and halt the flow of weapons and fighters into Eastern Ukraine.

"If Mr. Putin makes a decision that we are not going to allow heavy armaments and the flow of fighters into Ukraine across the Ukrainian-Russian border, then it will stop," Obama said. "And if it stops, then the separatists will still have the capacity to enter into negotiations and try to arrive at the sort of political accommodations that Mr. Putin himself says he wants to see. He has the most control over that situation, and so far, at least, he has not exercised it."

President Obama said the tragic shooting down of Malaysia Airlines Flight MH17 "will be a wake up call for Europe and the world" that the conflict between Russia and Ukraine could have broader consequences. (Associated Press)

Obama called for an immediate cease-fire in order to allow investigators to access the crash site and determine what happened to the plane. The immediate task, Obama said, is recovering the bodies of those who died. Obama said investigators from the National Transportation Safety Board and the FBI are in close contact with investigators.

"Our immediate focus will be on recovering those who were lost, investigating exactly what happened and putting forward the facts," Obama said. And, he added, it is very important not to rush ahead of them and contribute to misinformation.

"But I think it's very important for us to make sure that we don't get out ahead of the facts. And at this point, in terms of identifying specifically what individual or group of individuals or, you know, personnel ordered the -- the strike, how it came about, those are things that I think are still going to be subject to additional information that we're going to be gathering," he said.

Obama said the crash underscores the need for the violence to end in Ukraine.

"I think it's important for us to recognize that this outrageous event underscores that it is time for peace and security to be restored in Ukraine," Obama said, adding that Ukrainian government has put forward plans for a cease fire and a peace plan, despite "repeated violations" by separatists.

"Moreover, time and again, Russia has refused to take the concrete steps necessary to de-escalate the situation," Obama said.

Obama spoke with Putin Thursday morning about the expanded sanctions the United States imposed on Russia Wednesday. The U.S. targeted major banks, energy companies, the defense industry and individuals who are supporting separatists in Ukraine.

Obama said Putin "wasn't happy" about the sanctions. Obama stressed they were necessary because Russia continues to violate Ukrainian sovereignty and support separatists and is not pressing for a cease-fire. The United States, Obama said, will continue to "lead efforts within the world community" to support Ukraine and de-escalate the situation.

"So now's, I think, a somber and appropriate time for all of us to step back and take a hard look at what has happened. Violence and conflict inevitably lead to unforeseen consequences. Russia, these separatists, and Ukraine all have the capacity to put an end to the fighting," Obama said.

Obama said that the world is watching Ukraine.

"No one can deny the truth that is revealed in the awful images that we all have seen, and the eyes of the world are on eastern Ukraine, and we are going to make sure that the truth is out," Obama said.