The explosion shattered the windows of Salem Faraj’s flower shop last week. The attack, possibly by a homemade bomb or grenade, occurred in daylight across the street from a busy and heavily guarded hospital. No one was injured, but for Faraj it underscored this rebel capital’s violent and unpredictable landscape.

“We have no enemies,” said Faraj, staring at the destruction, as he struggled to search for an explanation. “We don’t know who did this.”

“Some kids probably did this,” offered Salem Mahmoud, a friend who had arrived to help clean up the mess. “They all know how to make bombs.”

At first glance, Benghazi appears to have returned to normality two months after the forces of Moammar Gaddafi entered on March 19. Shops are open; cars are clogging the streets. But beneath the surface, there is unease. Residents are taking the law into their own hands amid growing vigilantism.

In recent weeks, there have been several assassinations. Prosecutors say they are seeing more violent shooting attacks, including ones motivated by revenge, pitting neighbor against neighbor. Emergency room doctors are treating more gunshot wounds. Some are revenge attacks, others are over minor disputes.

“A lot more people have guns now. Before they had knives,” said Mustafa Abdisalam el-Diri, a doctor at Jalaa Hospital. “People use guns now to settle even simple arguments.”

The violence comes as the rebel leadership struggles to impose rule of law, as Benghazi is awash with weapons. Streets are still mostly patrolled by volunteer militias, rather than uniformed policemen. Gun battles between rival gangs, criminal, even rebels, are routine. There’s growing fear of a so-called fifth column of Gaddafi loyalists who are working to destroy the revolution and retake the city.

“We’re still in a situation of war,” said Ali Wanis, Benghazi’s chief prosecutor. “People are still living in fear of the regime. This will continue until Gaddafi falls.”

At Jalaa Hospital, some corpses have arrived showing signs of executions, bullets to the head, wrists with markings of being tied up. No one knows who is killing whom. Some believe the fifth column is carrying out attacks. Others believe the rebels are taking revenge on Gaddafi loyalists.

The fear has spread to many corners of Benghazi. In the Laity enclave, armed men guard the house of a well-known actress. Her son and brother were assassinated last week. Ali Abdullah, one of the guards, said the son was believed to have been a former member of Gaddafi’s internal security police.

In the Rahaba neighborhood, a father shook with fear when a journalist knocked on his door. His son, also a former internal security policeman, had been murdered in front of the house. The father looked nervously at his neighbor’s wall, then the sandbagged checkpoint manned by rebels on his street. “Let’s speak when the country is settled down, when there’s law and order,” he said, before closing the door.

In the Tabaleno neighborhood, residents have taken the law into their own hands. On a recent day, Adel Mohammed, a computer engineer, stood guard at a checkpoint, one of five entrances into the enclave. Behind sandbags, he clutched a Kalashnikov. Like many residents, he works eight-hour shifts, constantly keeping watch for strangers.

“The police are not in a position to help us,” Mohammed said. “Gaddafi’s groups are not far away. We can’t sleep and wait until they attack.”

At the flower shop, Faraj stood next to two friends, both clutching weapons. “We’re going to take precautions,” he vowed.

When told of the bombing, Wanis shrugged and replied: “I wouldn’t put aside that it was the fifth column who was behind the bombing. They want to make Benghazi appear insecure.”