Activists in Syria say hundreds of Sunni Muslims are fleeing the coastal city of Banias, fearing new attacks after the alleged mass killings at a nearby village.

The Britain-based Syria Observatory for Human Rights says the families started leaving the area early Saturday.

On Friday, Syria's main opposition group accused President Bashar al-Assad's government of committing a "large-scale massacre" in the northwest village of Bayda, killing at least 150 civilians, including children. Bayda is mainly inhabited by Sunni Muslims, who dominate the country's rebel movement.

In another development Friday, U.S. President Barack Obama said he cannot foresee any scenario where U.S. ground troops would be sent to Syria.

Mr. Obama said during a visit to Costa Rica that he does not rule anything out, but that putting "boots on the ground" would not benefit the United States or Syria.

The president said other leaders in the Middle East agree with him.

Mr. Obama declined to say what the United States would do if it proves the Syrian government used chemical weapons. He said it would turn over such evidence to the international community, but stressed that the United States must proceed carefully.

U.S. Defense Secretary Chuck Hagel said Thursday the Obama administration is reconsidering arming the rebels, but said no final decisions had been reached. The U.S. has been providing non-lethal aid to Syrian rebels.

Rights groups have accused both government and rebel forces of committing war crimes during the conflict, which has killed at least 70,000 people.