Violence persists in Syria at a time when Arab observers, who were dispatched to Syria last week to monitor the country's unrest, are preparing their first report on the situation in the unrest-hit country.

State-run SANA news agency reported Thursday the death of four army and police personnel.

A retired Colonel and his son, who was a Lieutenant, were killed by an armed group who fired at their car in the restive central province of Homs, SANA reported. After shooting the two officers down, the perpetrators pulled them out of their car and mutilated the body of the Colonel and fired multiple shots at his son.

In southern Daraa province, the birthplace of the Syrian unrest, an armed group attacked a police station in the town of Sour, killing two people, including the station's chief, and leaving six others injured, SANA said.

Meanwhile, two key activists' groups gave different tolls of casualties on Thursday.

The Britain-based Syrian Observatory for Human Rights said six people were killed in continued shooting of protesters in central Homs and eastern Deir al-Zour, while the Local Coordination Committees said 10 people were killed.

The violence took place as the Arab League (AL) observers continued its field job of overseeing the situation in the hotspots across Syria.

On Thursday, Arab teams toured in the Damascus suburb of Arbeen, two towns in southern Daraa, central Hama and northern Aleppo.

Head of the AL observer mission Moustafa Mohammed Ahmed al-Dabi is set to fly to Egypt's capital Cairo on Saturday to take part in a meeting of the Arab ministerial committee on Sunday to look into the mission's first report.

According to the AL, another 50 Arab observers will set foot in Syria on Friday, bringing the total number of observers in Syria to 140, according to Egypt's official news agency.

The new observers are from Algeria, Kuwait, Saudi Arabia, Qatar, the United Arab Emirates, Egypt and the Arab Organization for Human Rights. The announcement of the second team came just one day after the AL chief Nabil el-Arabi's reassertion that the observer mission will continue its work despite some parties are urging the AL to cancel it.

"We have a specific mission for a new month in which many things can be achieved," the AL chief said.

The Arab Parliament, an advisory body to the AL, urged on Sunday the AL to immediately stop the observer mission due to continued violence in Syria.

Meanwhile, Syria's Foreign Ministry spokesman Jihad Makdissi expressed his hope that observers will deal with the situation in Syria with professionalism and evenhandedness, adding that the Syrian government is providing everything to facilitate the mission.

Syria signed the AL observer protocol on Dec. 19, 2011 in Cairo after the AL threatened to take the issue to the United Nations Security Council.

The observers are in Syria to ensure that the government abides by its commitments agreed in the AL peace plan.

The Syrian government said some 2,000 army and security personnel were killed since the unrest began in March, 2011, while the UN said more than 5,000 people have died in the violence.