Pope Benedict XVI urged warring parties in Syria on Tuesday to end the 21-month-old civil war.

"May peace spring up for the people of Syria, deeply wounded and divided by a conflict which does not spare even the defenseless and reaps innocent victims," the pope said in his traditional Christmas message, delivered from the balcony of St. Peter's Basilica.

"Once again, I appeal for an end to the bloodshed, easier access for the relief of refugees and the displaced, and dialogue in the pursuit of a political solution to the conflict."

Sunni Muslims make up three-quarters of Syria's 22.5 million people. But Christians, who represent 10% of the population, have been drawn into the war, which has largely been fought by the Alawite-dominated government and the largely Sunni opposition.

Christians have been historically protected by the regime of President Bashar al-Assad, and have been reluctant to take sides. Some Christians in Syria abhor al-Assad, and others support the government. Many have been apprehensive about the prospects of an opposition government and fear the influx of jihadists in rebel ranks.

Jaramana, a town in the Damascus suburbs with a Christian and Druze population that has mostly been pro-regime, was the site of violence Monday night.

The opposition Syrian Observatory for Human Rights said rebels ambushed and killed a military intelligence officer there.

The Local Coordination Committees of Syria, an opposition network, said Tuesday that Free Syrian Army rebels killed five military intelligence soldiers in clashes with government forces.

A report issued last week by the U.N. Commission of Inquiry on Syria focused on sectarian hostilities and referred to dangers faced by Christians. It cited a car bombing outside a bakery in Jaramana and the kidnapping of Christians in September.

Before the conflict started in March 2011, the largest Christian communities were in the Damascus, Aleppo and Homs regions, it said. But many Christians have fled their homes because of the violence.

Homs Christians have escaped to Damascus, and some have made their way to Beirut; Armenians who had been living in Syria have sought refuge in Armenia.

Syria's Armenian Orthodox and other Christian communities "have sought protection by aligning themselves with the government, with the consequence that they have come under attack from anti-government armed groups," the report said.

Some Christians have formed "armed self-defense groups to protect their neighborhoods from anti-government fighters by establishing checkpoints around these areas."

More than 40,000 Syrians have been killed since March 2011, and hundreds of thousands have been displaced from their homes. At least 171 people were killed Tuesday, the LCC said. Of those, 61 died in Damascus and its suburbs.

The Syrian Observatory reported that rebel fighters had taken over the town of Harem in Idlib province. Regime forces and militia allies surrendered; many of them and pro-government civilians died during clashes, it said.

Tuesday's violence occurred after two days of air assaults on Syrians who had been waiting on line for bread. An air assault in Homs province killed at least 15 people Monday, a day after more than 100 were killed at a bakery in Hama province, opposition activists said.

Both bombings took place in areas known for anti-government sentiment. The state-run Syrian Arab News Agency (SANA) blamed "armed terrorist groups" for the Hama province attack.

Doctor: Mystery gas kills six, injures dozens

A doctor in Homs said six people have died after exposure to a mysterious gas. Dr. Abu al Fida said he treated about 30 of the more than 60 people who were affected by the gas this week.

Those who were close to the source of the gas suffered symptoms such as paralysis, seizures, muscle spasms and, in some cases, blindness, he said. Those who were farther from the source suffered difficulty breathing, disorientation, hallucinations, nervousness and a lack of limb control similar to excessive tear gas exposure, he said.