Almost every day of the uprising against the rule of Syrian President Bashar al-Assad has brought new reports of shootings, deaths and injuries.
Reports are hard to verify, as few journalists are allowed into Syria and casualty numbers come primarily from government and opposition sources. But there have been some major attacks that stand out as particularly violent episodes in an already bloody conflict.
This timeline outlines Syria’s massacres:
Deraa/Damascus, 22 April 2011
The Syrian uprising, then a month old, experienced its bloodiest day so far on 22 April when 72 protesters were killed by security forces firing on crowds.
Many of the dead were in the southern village of Ezra, near Deraa and in a suburb of Damascus.
Jisr al-Shughour, 3-6 June 2011
In June 2011, the Syrian government announced that 120 security personnel had been killed in the north-western town of Jisr al-Shughour.
The figure may have been inflated but it was a major attack and, as the BBC’s correspondent Jim Muir said at the time, it showed that the government was facing an armed uprising rather than mass peaceful protests.
Opposition groups initially denied they were behind the killings, but later investigations suggested that when protesters were fired on during a funeral, they attacked the state security forces. Some soldiers may also have been killed when they refused to shoot demonstrators.
Afterwards, thousands of residents fled Jisr al-Shughour fearing retribution from the army.
Jabal al-Zawiya, 19-20 December 2011
Villages in the area of Jabal al-Zawiya in Idlib province were the site of amassacre of army defectors in December last year.
Opposition activists said around 70 soldiers were mown down by machine-guns on 19 December after hundreds fled their positions between the villages of Kafrouaid and Kansafra. This was later backed up by eyewitnesses and a report by Human Rights Watch.
The London-based Syrian Observatory for Human Rights said a further 111 people – also mostly army defectors – were hunted down by the army and killed the next day in an “organised massacre”.
Homs, 3 February 2012
Syrian forces began shelling the restive city of Homs on 3 February, in what was to become a month-long bombardment.
Early reports talked of as many as 200 deaths, but one of the main activist groups later revised its confirmed number down to 55.
The BBC’s Paul Wood, who was in Homs travelling with fighters from the Free Syrian Army, described a city under siege.
Homs, 12 March 2012
The bodies of 45 people, mostly women and children, were found in the Karm el-Zeytoun neighbourhood of Homs on 12 March.
Most had their throats cut or had stab wounds, while others had reportedly been burned with heating oil and had their limbs broken.
Opposition activists and human rights groups said they had been killed by pro-government militiamen, the shabiha, who had entered the area after heavy government shelling.
Syrian state news blamed “armed terrorist gangs” for the killings, saying they had kidnapped residents of Homs, killed them and then filmed the bodies to discredit Syrian forces.
Taftanaz, 3 April 2012
Syrian forces entered Taftanaz in Idlib province. For two days, the army used helicopters and tanks to attack the town with shells and artillery.
The BBC’s Ian Pannell says Taftanaz now has two mass graves,holding approximately 57 people.
The attack on the town was part of a major Syrian army offensive in the area at the time, documented by Human Rights Watch in its report They Burned My Heart.
Houla, 25 May 2012
The village of Taldou, in the Houla region near Homs, witnessed one of the worst massacres in Syria’s uprising.
UN observers confirmed that 108 people were killed, most of them women and children. Some had been killed by shell fire, but the majority had been shot at point-blank range or stabbed.
The government blamed terrorists, but survivors and human rights groups pointed the finger at the army and shabiha militiamen allied to the government.
Hama, 6 June 2012
At least 78 people, many of them women and children, were killed in a single village in the central Hama province, according to activists. Most of those who died had been stabbed and shot.
According to activists, government-backed militia were behind the deaths in the village of Qubair.
The government, meanwhile, has said that a “terrorist group” carried out the killings and claims that only nine people died.
Tremseh, 12 July 2012
There are conflicting reports from Syria about the deaths of dozens of people in Tremseh, a village in Hama province.
Opposition activists and witnesses said army tanks bombarded the village for several hours before pro-government militiamen swept in, shooting and stabbing victims at close range. They reported that as many as 220 people were killed, including a number of rebel fighters.
The Syrian government said at least 50 people were killed in Tremseh, but it blamed “armed terrorist groups”.
Scores of people have also died in a series of bomb attacks on Syria’s main cities.
Many of them have targeted security facilities. The government blames anti-regime forces and Islamist groups linked to al-Qaeda.
Opposition activists, meanwhile, maintain that the government is responsible for the attacks, alleging security forces plant the bombs themselves in order to discredit anti-government protesters.
Analysts suggest that it would not be beyond the realms of possibility for the security services to plant bombs.
There are reports that, in some of the attacks, officers had cleared the area in advance and security cameras had been taken down.
But UN Secretary General Ban Ki-Moon blamed al-Qaeda publicly for a car bomb in Damascus on 10 May.
A shadowy Islamist group, the al-Nusra Front, has also said it was behind for several suicide bombings.
Bombing deaths• 23 December, Damascus: 44 dead
• 6 January, Damascus: 26 dead
• 10 February, Aleppo: 28 dead
• 10 May, Damascus: 55 dead
• 19 May, Deir ez-Zour: 9 dead
Casualty figures come primarily from Syrian government sources and are not verified