Witnesses say Syrian forces and tanks are massing outside the northern city of Jisr al-Shughour after hundreds of its residents fled across the border to safety in Turkey to avoid an anticipated government assault.

Residents say about 40 tanks and troop carriers have deployed about seven kilometers outside the city of 50,000. The Syrian government has accused “armed gangs” in the border region of “massacring” more than 120 security personnel earlier in the week and vowed retaliation. Witnesses say that many residents have already left the city, crossing olive groves on foot or in vehicles to get to Turkey.

Meanwhile, pro-democracy activists called for new protests Friday against the authoritarian government of Syrian President Bashar al-Assad. Rights groups say at least 1,100 people have been killed in the Syrian crackdown against anti-government protests that began in March and more than 10,000 people have been arrested.

Turkish Foreign Minister Ahmet Davutoglu said Thursday more than 2,500 Syrians have entered his country and Turkey says it has no intention of closing its borders. The influx prompted Turkish authorities to set up three camps to handle the crisis.

Residents said thousands more people have escaped to nearby villages just inside Syria and are prepared to cross into Turkey at any time.

The northern region has become the focal point of the Syrian conflict. Refugees and residents there have described a mutiny among soldiers who either defected or refused to fire on civilians after a pro-democracy rally in Jisr al-Shughour a week ago. They said loyalist military units then attacked the rebellious troops.

Meanwhile, diplomatic efforts are unfolding at the United Nations.

Russia said Thursday it opposes a U.N. Security Council draft resolution condemning Syria for its crackdown on anti-government protesters. Foreign Ministry spokesman Alexander Lukashevick says Syria's unrest does not pose a threat to world peace or security.

He commented a day after European members of the Security Council presented a revised resolution calling for an immediate end to the violence in Syria and for humanitarian access. It also urges Syria's government to enact genuine political reforms.

Separately, the U.N. High Commissioner for Human Rights has accused Syria of trying to “bludgeon its population into submission” with its crackdown on protesters. Navi Pillay said Thursday it is “utterly deplorable” for any government to deploy tanks, artillery and snipers against its people.