Activists say Syrian troops continue to fire upon neighborhoods in the opposition stronghold of Homs. The weekend of violence there is raising new doubts about President Bashar Assad's commitment to end the 13 months of bloodshed.
The U.N. monitors are in Syria to observe the shaky cease-fire. A top U.N. official says more observers are expected to arrive within a couple of days.
Assad accepted the truce deal at the prodding of his main ally, Russia, but his compliance has been limited. He has halted shelling of rebel-held neighborhoods, with the exception of Homs, but ignored calls to pull troops out of urban centers, apparently for fear of losing control over a country his family has ruled for four decades.
The Associated Press contributed to this report.