May was the bloodiest month in El Salvador since the end of the civil war in 1992, with 635 reported homicides blamed on the small country's street gang warfare.
At least 20 people were killed in the country of 6.1 million every day between May 1 and May 31, the Associated Press reported. By comparison, at the height of the country's civil war between 1980 and 1992, on average 17 people were killed a day.
"This is the most violent month since 1992, and we know that there is even underreporting," Miguel Fortin Magana, director of the Supreme Court's Institute for Legal Medicine, told AP in an interview.
May 19 was the most violent day in the month for El Salvador, in which 34 people were killed over the course of 24 hours. National police director Mauricio Ramirez Landaverde said 60 percent of those killed last month were victims of gang violence.
March in El Salvador saw 481 homicides, making that month the deadliest since the end of war before May's tally — equaling a 32 percent increase over the previously highest homicide record.
The so-called Northern Triangle in Central America — containing El Salvador, Honduras, and Guatemala — has some of the highest homicide rates in the world, and in some cases entire communities are under gang control. Homicides in the region are rarely investigated and prosecuted successfully.
According to a January report by a Mexico-based policy research center, San Salvador, the capital, ranks thirteenth on the most recent list of world's most violent cities, excluding war zones.
June so far appears to have begun violently as well: at least five people were killed in the country on Tuesday, reports said.
Authorities said the spike in violent crime could be meant to apply pressure on the government to negotiate jail conditions for gang kingpins who were recently transferred to maximum-security prisons in the country.
El Salvador briefly enjoyed a dip in homicides during the 2012 gang truce brokered by the government. But since the agreement was called off in early 2014, violent crime is once again on the rise.
In spite of the truce's success, President Salvador Sanchez Ceren has said he will not look to broker a new agreement. "We won't negotiate with any gangs," Sanchez said in February.
The Associated Press contributed to this report.