The two explosions that ripped through Beirut Tuesday evening killed at least 78 people and wounded thousands more. The second, far larger blast devastated a wide area, with the shock wave knocking people down, overturning cars and enveloping much of the center city in a cloud of dust and smoke. Windows of apartment towers miles away were blown out, leaving the city’s streets looking as if they had been “cobbled in glass,” according to a resident.

The injured, at least 4,000, were soon streaming into local hospitals, often arriving on foot or carried by friends and family members, with streets made impassable to cars and local ambulance services overwhelmed. St. George Hospital in central Beirut, one of the city’s biggest, was so severely damaged that it had to shut down and send patients elsewhere. “Every floor of the hospital is damaged,” said Dr. Peter Noun, the hospital’s chief of pediatric hematology and oncology. “I didn’t see this even during the war. It’s a catastrophe.”

The government said “highly explosive materials” had been stored where the explosions occurred, in Beirut’s northern, industrial waterfront, with many hospitals, mosques, churches and universities nearby. As of Tuesday night it remained unclear if the blasts were the result of an accident or an intentional attack.

Lebanon’s government had already been facing large protests over an economic collapse, mismanagement and corruption. “Those responsible will pay a price for this catastrophe,” said Prime Minister Hassan Diab. “This is a promise to the martyrs and wounded people. This is a national commitment.”

Whatever the cause, the explosions stirred memories of Lebanon’s 1975-1990 civil war, and its aftermath, when bombings and other attacks were a regular occurrence. For all its economic and other woes, Beirut had been relatively peaceful in recent years before Tuesday’s blast shattered much of the city.