(CNN) -- The death toll in Syria hit 343 Wednesday, the highest daily toll since unrest broke out in March 2011, an opposition group said.
"The regime is escalating the violence at every possible opportunity and it is proof that it is determined to crush the revolution by any means necessary," said Rafif Jouejati, a spokeswoman for the Local Coordination Committees of Syria.
"The staggering numbers are horrific but the world also needs to know that there is increasing sexual torture and more children being tortured."
Jouejati accused the Syrian regime of being willing to commit genocide. "There is (a) systematic increase in the violence and the world powers -- so far -- have shown that they are not willing to do much beyond the same condemnations we have been hearing for the last 19 months."
The highest death count on Wednesday occurred in Damascus and its suburbs, where LCC cited 162 deaths, including 107 in a reported massacre in Thiabieh.
The second-deadliest day occurred August 25 of this year, when 330 people were killed, according to the opposition group.
Wednesday's violence came as Syrian rebels attacked a key government military facility in the capital city of Damascus, the second such strike in two days.
Four guards were killed and 14 people were wounded, including civilians and soldiers, state television reported.
'The government said a fight was under way to expel "terrorists" from the building -- the office of the joint chiefs of staff -- but that the country's military officials were not affected.
Activists, however, said their forces had inflicted dozens of casualties in the attack.
Syrian state television reported that the attackers used two suicide car bombs in their assault on the military facility. The Free Syrian Army, a prominent armed group battling government forces, said it was responsible for the strike.
Damage to Syria's army headquarters was extensive, charring its interior, reported Bill Neely, a correspondent for UK broadcaster ITN . A crater outside the facility marked the spot where a car bomb had detonated.
Closed-circuit television images showed a white van driving near the headquarters before exploding.
The location of the battle, in the heart of the capital, means that government forces are defending what had been among of its most secure facilities.
Since the unrest started in March of last year, more than 30,000 people have been killed, the opposition Syrian Observatory for Human Rights said. The figure includes 21,534 civilians, 7,322 Syrian army forces and 1,168 defectors who joined the rebels, the group said. Previous estimated death totals from the United Nations and opposition groups ranged from 18,000 to 21,000. CNN cannot independently confirm the figures.
In other reports about the attack on the military facility, Iran's state-run Press TV said one of its correspondents was shot and killed and another was wounded.
Maya Naser, 33, was killed by a rebel sniper; the station's Damascus bureau chief, Hossein Morteza, was wounded, Press TV said.
The journalists were covering fighting that followed a pair of blasts in the capital, the station said.
"We hold Turkey, Saudi Arabia and Qatar, who provide weapons and militants to kill civilians, military personnel and journalists, responsible for killing Maya," said Hamid Reza Emadi, Press TV's newsroom director.
At least 21 other journalists have been killed covering the Syrian civil war since November, making the nation the most dangerous place in the world for journalists, according to the Committee to Protect Journalists.
The brazen assaults on military facilities in the capital city show the resilience of a rebel force that has shown no signs of slowing.
The government blamed the attacks on the military sites on "terrorists," a term it consistently uses to describe anti-regime fighters. It vowed to continue its "unyielding fight" to confront terrorism.
Qatar's PM: 'We have a Plan B for Syria' The Syrian crisis broke out in March 2011 after unarmed protesters, inspired by the success of popular uprisings in Egypt and Tunisia, took to the streets demanding political reform and an end to four decades of rule by the family of President Bashar al-Assad.
The movement devolved into an armed conflict after a brutal and continuing crackdown by al-Assad's forces.
CNN's Amir Ahmed, Faith Karimi and Nick Paton Walsh in Lebanon contributed to this report.