Among the world's many gloomy corners, it is hard to get any gloomier than Brazil. After a drug war broke out among several criminal groups, leading to huge prison riots and the death of close to 100 inmates, what looks like a worrying yellow fever outbreak and the death of the Supreme Court judge leading the ongoing Lava Jato ("Car Wash") anti-corruption probe, the northern city of Belém set a new 24-hour record for the number of homicides in a locality, with 30 deaths.

As Folha de S. Paulo reports, the wave of killing started on Friday morning, after a 29-year-old military police officer, Rafael da Silva Costa, was killed during a shootout with criminals he was chasing. By Saturday morning, 30 more people had been killed around the city, with at least 25 of them showing signs of having been executed, local security officials said. "We are considering the possibility that these crimes were committed in reaction to the policeman's death, but we can't say this with certainty yet," the Pará state's security secretary Hilton Benigno told reporters. Witness reports would seem to confirm this, pointing out that many of the killings looked like they had been the work of militia gunmen, driving around in black cars.

Some of the victims just seem to have found themselves at the wrong place, at the wrong time. Among them, a 23-year-old cab driver, whose family say he was not a criminal and "just minding his own business." "Nobody knows why they've killed him," a cousin of the driver told another Folha de S. Paulo reporter.

As a result of the wave of bloodshed, many people decided to keep their shops closed over the weekend. "We're scared because anybody could be next," mechanic José Henrique Nunes said. "On the one hand, you have the local criminals we all know. On the other, you have the militiamen driving around and killing people."

In one neighborhood where a man was killed with 13 bullets on Friday afternoon, some people locked themselves up at home. "We avoid leaving the house out of fear. We're surrounded by violence on all sides," a 21-year-old student and neighbor of the victim said.

The authorities, however, consider that the situation was brought under control before noon on Saturday. Between 12 p.m. on Saturday and the same time on Sunday, "only" six people were killed. That would be seen as an awful and utterly unacceptable lot in some places — but in Belém, it's just an average weekend.

The explosion of crime is hardly limited to Belém. In the coastal city of Natal, in the Rio Grande do Norte state, public transport was interrupted on Thursday after a wave of criminal attacks in which 26 buses, as well as five government cars and three public buildings, were torched. This happened despite — or perhaps because of — the presence of military police at the city's Alcacuz prison, where at least 26 inmates were killed over the past 10 days. In Natal too, the situation eventually returned to normal and public transport services resumed on Monday. But how long it will last is anybody's guess.

See more from World Affairs here