(CNN) -- More than 100 people were killed Monday in and around the northern Syrian city of Jisr Al-Shugur in the third consecutive day of violence there, according to reports from the government and opposition groups.

State television cited 120 security forces killed, including 82 in Jisr Al-Shugur. In addition, it said, dozens of civilians were wounded.

State television said the security forces were killed in several attacks including an ambush by "armed gangs" in the city, when government buildings were set afire, and in clashes at a security center.

"The armed attacks targeted public and private buildings in various regions and lately there were similar attacks in Jisr Al-Shugur," Interior Minister Mohammed Ibrahim al-Chaar said in a short statement on state television. "The state will deal with sternness and force within the law and we will not remain silent when it comes to any armed attack."

State television further reported that the "armed gangs" had stolen five tons of dynamite from a storage area near the Al Abyad Valley Dam.

Al Arabiya reported that the "Syria opposition is pleading for the military not to shell their city with their tanks."

In a statement read on state TV, Minister of Information Adnan Mahmoud said the people of Idlib District "were horrified" by the attacks, and accused the "armed gangs" of using medium-range weapons and bombs and using civilians as human shields.

But tweets and social media websites said the clashes took place when soldiers defected, refusing to follow orders to storm Jisr Al-Shugur.

State-run Syrian Arab News Agency said armed groups had barricaded themselves in some areas and were using machine guns and hand grenades.

The state security forces were facing hundreds of armed men in Jisr Al-Shugur and were trying to lift the siege of a neighborhood that had been taken over by the "gangs," state TV reported.

It said the state was sending reinforcements.

A resident of Jisr al-Shugur said earlier that the city was calm Monday, and that the clashes happened at nearby Khan Shaykhun, where 20 residents and an unknown number of security forces were killed.

He said residents were using hunting rifles.

The Syrian Revolution Facebook page said 10 helicopters were firing at civilians. The page predicted a major military incursion Monday night and appealed to residents to evacuate as soon as possible to Turkey.

Turkish officials in the border region said late Monday they had seen an increase in refugees and wounded Syrians in recent days.

Forty-one Syrians crossed Saturday into Turkey, local officials in the Yayladagi border town said.

Among them were injured Syrians who were taken to a hospital, witnesses said. The rest were taken to a tent camp set up by the Turkish Red Crescent in the Yayladagi town of Hatay province.

About 200 Syrian refugees have been living in the camp, which was erected on the grounds of an old tobacco factory, since late April/early May. They are not allowed to leave the compound and journalists are not allowed to meet with them.

A doctor from the regional hospital where some of the injured were taken said last weekend's arrivals -- about 30 in all -- had suffered mostly gunshot and shrapnel wounds and were from Idlib, in Syria's northwest.

An opposition member who lives outside Syria but has sources inside the country who have proved reliable in the past said the clashes over the past three days in Jisr Al-Shugur, Khan Shaykhun and surrounding villages were between members and supporters of the Islamist group the Muslim Brotherhood and the Syrian security forces.

He said that 90 security members and 23 opposition members were killed Monday. In addition, nine tanks were destroyed and two helicopters were downed, he said.

He said the weapons had been taken into the country from Turkey, whose border is about 20 kilometers away. The wounded, he added, were being taken to Turkey for treatment.

The man, who has asked not to be identified for fear of reprisal, said Muslim Brotherhood supporters have long opposed the Syrian regime and were taking advantage of the uprising to settle their score. He further expressed concern that the brotherhood could hijack the peaceful secular uprising.

The Arabic Facebook group called the Local Coordination Committees of Syria reported that 42 people died Sunday in Jisr al-Shugur and its suburbs as the Syrian army and security forces sought to enter the city, where many of the stores have been closed in a general strike.

The Syrian Observatory for Human Rights put Sunday's death toll at 47 -- 37 civilians and 10 security forces.

CNN was not able to confirm the reports. The Syrian government has restricted access to the country by members of the international news media and reliable information has been hard to get.

For example, two videos posted over the weekend on YouTube showed what Syrian opposition activists said was the slaughter of civilians in the besieged city of Daraa in the south of Syria. One video shows what appears to be a group of Syrian security forces standing over dead bodies, making jokes and discussing planting weapons on them.

The images included the bloody, mangled bodies of five men in civilian clothes. Men dressed in military uniforms walked around them, talking. "Show me those weapons," one said, "put them here."

Someone dropped what appeared to be weaponry onto the torso of one of the bodies.

"These are the weapons the committee will come film," a voice said.

Throughout the uprising in Syria, the Syrian government has described protesters as "armed criminals" and "terrorists," at times saying photos prove that the "criminals" were armed when security forces shot them.

The videos -- in which the bodies are bleeding from different areas -- are labeled online as having been shot April 30.

CNN cannot independently confirm the authenticity of the videos.

The number of people killed in the government's crackdown on demonstrators, which began in mid-March, has exceeded 1,000, according to the United Nations.

Despite international calls to halt its aggression and sanctions by the United States, Syrian President Bashar Al-Assad has shown no sign of backing down.

CNN's Saad Abedine, Arwa Damon, Yousuf Basil, Ivan Watson and Nada Husseini contributed to this report.