(CNN) -- "At one point we killed eight people in 15 minutes. The protesters were unarmed. They didn't even have rocks! That's when I decided to defect. I threw away my gun and ran towards the protesters."
"About 1,500 protesters came.....They requested the release of an injured protester who was inside the hospital. They held olive branches. They had no arms. There were 35 army soldiers and about 50 mukhabarat personnel at the checkpoint. We also had a jeep with a mounted machine-gun. When the protesters were less than 100 meters away, we opened fire."
These statements are part of the testimony of two Syrian soldiers who say they deserted after being ordered by officers to fire on unarmed protesters.
They are among 63 who have fled to neighboring countries and told Human Rights Watch of their experiences. The organization has documented incidents where soldiers say they were ordered to kill or torture protestors, went on looting rampages or witnessed other soldiers being shot or tortured for disobeying orders or desertion.
The report, released Thursday, is titled, "By All Means Necessary," borrows the language allegedly used by officers as they issued orders to soldiers to put down protests. It identifies 74 commanders and officials accused of ordering attacks on unarmed protestors.
The testimony is frequently harrowing. A soldier from the 9th Division recounted that on April 28 he was sent to a checkpoint to prevent protesters from marching on the capital, Damascus.
"People were approaching from different sides, and one guy came up to me and screamed, "'If you are a man, shoot me!' The same moment, a mukhabarat guy next to me shot him in the shoulder, at close range, and tried to arrest him. His mother approached us and said, 'Let him go; take me instead!,' and a mukhabarat guy in civilian clothes in front of me shot the guy point blank and killed him, in front of his mother."
The mukhabarat are members of the the feared military intelligence service regarded as regime loyalists.
At about the same time - in Daraa, where the protests began - a soldier alleged that his commander stood in front of the brigade and ordered: "Use heavy shooting. Nobody will ask you to explain."
Another soldier deployed to Bukamal in May said his commander made it clear that the unit's "job was not to arrest people, but to kill."
According to the soldier, the commander gave verbal orders to "kill anyone putting up resistance, regardless of whether they are men, women, or children."
HRW says it interviewed 63 defectors from the armed forces over a period of six months, talking to them "and other witnesses separately and at length.
"Violations described in this report are those that several defectors described separately," HRW says.
Most of the interviewees were conscripts but several were officers.
One soldier said in the early days of the protests, commanders would brief their men "about how good Assad and his family were, and about the threats from the terrorists. And then they also forbade us from taking leave."
Many of the soldiers said they were convinced that the government's claims were false when they went on leave and realized that "close relatives and friends were participating in the protests and had been attacked by the security forces."
The Syrian government continues to maintain that "armed gangs" and terrorists, incited from outside Syria, have been attacking the security forces.
In an interview with the U.S. network ABC a week ago, President Bashar al Assad said he was not responsible for any misconduct by the security forces. "I don't own them. I'm president. I don't own the country, so they're not my forces," he said.
But some of the soldiers interviewed by HRW accuse senior officers close to the president of ordering them to shoot protestors. One man who says he served in the 4th Division said a brigadier general had instructed them to shoot at protestors in Damascus. He says he later found out that "the orders came from Maher al-Assad, de facto commander of the 4th Division and President al-Assad's younger brother."
Another soldier with the 4th Division said that his unit was deployed to make arrests in a Damascus neighborhood in May.
"We had batons, and the shabeeha (a government militia) had weapons; they wore black clothes. We were running after people, and those we grabbed wished they had died because of how badly we beat them."
A captain "used to shoot with his pistol at those we couldn't catch."
A former lieutenant colonel in the Presidential Guard described the torture of a man on the "wanted list" who had been detained in a suburb of Damascus in August.
"When I came, he was still alive," the former officer related. 'He was screaming, and the soldiers were swearing and laughing. It lasted for about five minutes longer, and then he died."
The report also details ruthless treatment of soldiers who tried to avoid killing protesters. One soldier said that during a protest in Damascus in April, a young conscript called Yusuf was shooting in the air and not at protestors. A military intelligence officer "called a sniper on the roof, pointed at Yusuf, and the sniper then shot Yusuf twice in the head. Intelligence agents took Yusuf's body away. The next day we saw Yusuf's body on TV. They said that he had been killed by terrorists."
The soldiers also describe "sweeps" of neighborhoods where protests were common, with hundreds of arbitrary arrests.
Among incidents of looting described, one soldier said that "in Bayda we broke the doors and took whatever we wanted. The mukhabarat was arresting people; in one area, they arrested ten old men to force their children to turn themselves in. The same continued in Banyas, where we went the next days. In Basateen, we looted everything, both my unit and others."
HRW says defections from the Syrian armed forces and intelligence agencies appear to have steadily increased since the protests began in March.
HRW says the UN Security Council should ensure the accountability of the officers named "up to the very highest levels of the Syrian government" by referring Syria to the International Criminal Court.
"Try as he may to distance himself from responsibility for his government's relentless brutality, President Assad's claim that he did not actually order the crackdown does not absolve him of criminal responsibility," says Anna Neistat, one of the report's authors.
"The ongoing killings, arrests, repression, and general denials of responsibility by the Syrian government also make clear that officials have failed to take any meaningful action to address these abuses," HRW concludes.
The UN High Commissioner for Human Rights estimates that some 5,000 people have been killed in Syria's unrest. On Wednesday, UN Secretary-General Ban Ki Moon said: "This cannot go on. In the name of humanity, it is time for the international community to act."
The report comes out a day after there were unconfirmed reports that 33 people were killed in Syria. The deaths were reported by the Local Coordination Committees of Syria, an opposition group that organizes and documents protests.
CNN cannot independently confirm reports of violence in Syria because the government restricts access by foreign journalists.