Government troops in Syria have broadened shelling attacks on opposition areas, casting more doubt on a U.N.-backed ceasefire brokered by special envoy Kofi Annan. The number of people killed in Syria has been rising steadily after a brief moment of quiet when the ceasefire took effect last Thursday. On Monday, at least 26 people were killed across the country, although one activist group put the death toll at 55. Activists say shelling by government tanks killed at least two people in the southern town of Busra al-Harir. At least five people were killed when the government shelled parts of the central city of Homs in an apparent push to claim the last remaining rebel strongholds there. A six-member advance team of U.N. observers arrived in Syria over the weekend, and more monitors are expected to arrive this week.