(CNN) -- Tensions flared outside the Syrian capital of Damascus on Tuesday as reports surfaced of a massive funeral for a man apparently shot dead by security forces in one town and two police officers apparently killed during a patrol elsewhere.
Eyewitness Abou Assad told CNN that around 6,000 mourners were in Moathamia for the funeral of Ahmad al Doumarani, a gathering that turned into the latest mass display of anti-government fervor in the restive country.
The witness said security forces killed al Domarani and wounded two other men early Tuesday, and al Domarani's burial was held later at a mosque. He added the men were workers and were headed home, but he couldn't provide any further detail about why and how the violence occurred.
CNN cannot independently verify witness accounts from Syria.
Syrian TV reported that unidentified men shot and killed two police officers, Hassan Maala and Hameed Al-Khatib, during a routine patrol in the town of Kafar Batna. There were no further details.
Demonstrators in Syria have been incensed at what they see as President Bashar al-Assad regime's heavy-handed rule, and they have embarked on anti-government protests for nearly three weeks.
Opponents of the government allege massive human rights abuses and are calling for political and economic reform. They also want the release of all political prisoners and an end to emergency law.
The emergency law allows the government to make preventive arrests and override constitutional and penal code statutes. In effect since 1963, it also bars detainees who have not been charged from filing court complaints and from having a lawyer present during interrogations.
Two humanitarian groups -- the International Federation for Human Rights and the Damascus Center for Human Rights -- have released the names of 123 people killed between March 18 and Friday.
Human Rights Watch on Tuesday -- which says at least 100 demonstrators and bystanders have died since March 16, according to lists from human rights groups -- urged al-Assad to halt using "unjustified lethal force" against protesters.
It said the government should probe each shooting and "hold accountable anyone responsible for the unlawful use of force."
"For three weeks, Syria's security forces have been firing on largely peaceful protesters in various parts of Syria," said Sarah Leah Whitson, Middle East director at Human Rights Watch. "Instead of investigating those responsible for shootings, Syria's officials try to deflect responsibility by accusing unknown 'armed groups. ' "
Demonstrators took to the streets Friday, and violence occurred in the Damascus suburb of Douma, where at least eight demonstrators and possibly as many as 15 died.
An unnamed official told the official Syrian Arab News Agency over the weekend that an unknown "armed group" on rooftops shot at protesters and security forces. Activists said they believe the people on the rooftops were snipers from security forces.
After protesters left the Great Mosque in Douma following Friday prayers, they "found hundreds of riot police and men dressed in civilian clothes, probably from the security services, waiting for them," witnesses told Human Rights Watch.
Two Douma demonstrators told Human Rights Watch that "they believed the gunmen were from security services because they were standing with their weapons behind the riot police."
"The police and the mukhabarat started beating us and launched tear gas canisters to force us to disperse," one of them said, referring to Syrian intelligence. The forces also detained protesters when they departed from the mosque.
Witnesses said protesters hurled rocks at the police, but none carried any firearms.
One protester told Human Rights Watch "suddenly, at around 3 p.m., we heard live bullets being shot. I saw one protester die and I started running away and found shelter in the stairwell of a neighboring building. For the next two hours, I heard shots being fired. It sounded like they were firing their Kalashnikovs. At around 5:30 p.m., the situation calmed down."
Human Rights Watch said that under the U.N. Basic Principles on the Use of Force and Firearms, lethal force can only be used "when strictly necessary to protect life" and "force must be exercised with restraint and in proportion to an imminent threat." It said rock-throwing can't justify such force.
"Syria's judicial authorities need to show that they are independent and able to investigate the responsibility of senior security officials who allegedly sent men with firearms to police the protests," Human Rights Watch's Whitson said.
CNN's Joe Sterling and Tracy Doueiry contributed to this report.