Fighting is continuing in several parts of the Syria ahead of a proposed ceasefire, and Syrian government forces have opened fire across the Turkish border.
Turkey mounted an official protest after the attacks, the first to spill over the border since the country began housing refugees from the Syrian unrest.
The attacks left at least two people dead and many injured.
A military bombardment of a town in central Syria killed 35 people on Monday on the eve of a scheduled army withdrawal, opposition activists said.
A UN-brokered plan requires the government of President Bashar al-Assad to begin pulling back troops from towns and cities by Tuesday, paving the way for a ceasefire.
Over the weekend, President Assad demanded written guarantees from opposition leaders that their forces would stop fighting and lay down arms.
The United States has dismissed the demand for written guarantees as a stalling tactic.
