BEIRUT — Before the first explosion, Laila and fellow architecture students at Aleppo University in Syria had gathered by chance in a stairwell, which shielded them from flying glass and shrapnel.
In an instant, the less fortunate lay dead and injured amid the scattered debris.
A second blast a few minutes later hit a dormitory across the street, causing more casualties.
The twin explosions two weeks ago that killed more than 80 people and wounded 150 also left Laila determined to return to the university as exams and normal class schedules resumed Tuesday for the first time since the blasts.
"If we don't continue attending classes, we will become a backward country," said Laila, 22, who used her Red Crescent training to aid victims at the chaotic scene.
The blasts, apparently caused by a pair of missiles, were among the deadliest and most stunning of Syria's almost two-year civil conflict, spurring global revulsion at a frontal assault against one of the nation's leading educational institutions. The targeting of the university stood out as an appalling act even amid a withering conflict that has seen an ever-escalating death toll, now more than 60,000, according to the United Nations.
The perpetrators remain unknown. No one has taken responsibility.
Each side in the war between forces loyal to President Bashar Assad and opposition fighters blames the other. Each has sought to score propaganda points from the carnage.
Still, no definitive evidence has emerged linking either side to the atrocity.
That is often the case now in Syria, where mass killings of civilians regularly spark outrage, grief and bitter accusations, but no hint of accountability. Independent investigation is often impossible, as outside access to the war zone is limited.
The bruised and battered city of Aleppo, once Syria's thriving commercial hub, witnessed its latest atrocity Tuesday: The bodies of dozens of young men, many handcuffed and with bullet holes in their heads, apparent victims of summary execution, were found in a muddy riverbed, opposition activists reported.
Impunity reigns, even as world panels threaten vaguely of war crimes prosecutions to come. Bodies are buried, mourners weep, the debris is swept away, and life goes on, as it does this week at Aleppo University despite the horrific memories.
It was about 1 p.m. on Jan. 15 when the first of the explosions rocked the university's sprawling, tree-lined campus. The blast appears to have occurred outside the architecture building, where Laila and other students were gathering inside for midyear exams.
The dormitory hit by the second strike housed displaced civilians from the city's battered front-line districts. Most casualties were there, among desperate people already coping with homelessness.
An amateur video seems to have captured the moment of the second strike. The person holding the camera approaches a column of black smoke, probably from the first explosion. Several multistory buildings, apparently a dormitory block, are visible on the right. Suddenly, a roar is heard and an explosion of flame engulfs the buildings. A mushroom cloud of thick, gray smoke billows into the clear-blue midafternoon sky.
Photos of the aftermath show the facade sheared off the dormitory, revealing cubicles spilling out beds and other furniture, random artifacts of former lives. Human remains were blasted out into the street, where vehicles were set ablaze and the dead lay among the grievously wounded.
"We saw body parts everywhere, in the trees, on the ground," said Semoon, a second-year dentistry student, who, like others interviewed, did not want his full name used for security reasons.
The attacks came at a time of relative calm in Aleppo, when a spell of inclement weather and a shift in rebel strategy toward attacking bases outside town had resulted in a lull in government bombardment.
Opposition activists say warplanes firing missiles were the culprit. As evidence, the activists cite witness accounts of streaking aircraft at the time of the strikes. The motive is clear, they say: Payback for Aleppo University's standing as a longtime hub of protests against the government.
The U.S. State Department backed the opposition allegation, saying Washington was "appalled by the Syrian regime's deadly attack." Russia, Assad's ally, called the notion of government involvement "blasphemous."
The accusation that the military launched the attack, however, raises a question: Why would the government bomb a campus well within its zone of control?
Since July, when rebels slipped into Aleppo, the city has been roughly divided into opposition and government-held sectors. The front lines have mostly held as the battle has turned into a protracted stalemate, mirroring the standoff nationwide.
The Syrian military has made extensive use of warplanes and artillery in the city and its environs. But government firepower has been concentrated on rebel-held areas or disputed front lines, not government-controlled areas like the university campus.
Syrian authorities, for their part, lay the blame for the attack on "terrorists" who, according to the official account, fired a pair of rockets from Al Lairamoun, an industrial area to the north largely under rebel control. The motivation, said the official Syrian news service, was to punish residents for their loyalty to the government.
Opposition representatives deny that the rebels possess missiles capable of causing such destruction. But insurgents are known to have seized vast stocks of weaponry from overrun government bases and armories.
Rebels have detonated car bombs in loyalist districts of Aleppo, including multiple blasts in a central square in October that left dozens dead. Initial reports of car bombs in the university explosions now appear erroneous, however.
Some observers suspect that the campus was not the intended target and was struck by mistake. Neither side in Syria is known for the accuracy of its fire.
Whoever was behind the attack, the bombings cast a pall of anger and grief over Aleppo University. Students held multiple memorial ceremonies. Several sessions erupted into antigovernment protests.
The victims memorialized on social media sites included Fahed Miri, remembered as a tireless young medical volunteer who would sleep at the university dormitory after spending his days lending a hand at hospitals and clinics. Miri did not have a high school degree, medical training or a home. But the fierce fighting last summer in his ravaged front-line neighborhood, Salahuddin, inspired him to service.
"When the first missile hit Salahuddin neighborhood, I saw that I was helpless, so I turned to the medical field to help as many people as I could," Miri once explained to a friend, according to a Facebook posting.
Among some students, a feeling has emerged that returning to classes somehow slights the memory of those who perished. Laila and others share an opposite view, that abandoning their studies would signal a triumph for the dark forces behind a barbaric act.
"I know there are many people who don't want us to go back to school. They think it is disrespectful to the blood of the martyrs," said a 22-year-old fine arts student. "But what can we do? Stop our studies?
"Education is not a luxury.... We are fighting something bigger than we are: a regime that will not go away with a protest, a strike or a sit-in."
Selo is a special correspondent. Special correspondent Alaa Hassan in Beirut and Times staff writer Raja Abdulrahim in Los Angeles contributed to this report.