A total of six Salvadorans have been arrested for their involvement in a shootout that left six people dead in downtown San Salvador, the head of the National Civil Police (PNC), Howard Cotto, confirmed at a press conference on Thursday.

Cotto said that private security guard Hector Antonio Morales, 52, was murdered by three members of the Mara Salvatrucha (MS13) gang, one of whom was captured by security forces.

The PNC director said that the arrested gang member, who was wounded in an exchange of gunfire with police, is Kenen Garcia, a “member of the MS13 gang that operates in downtown San Salvador.”

The other people arrested were identified as Salvador Hernandez, Kevin Moreno, David Melara Perez, Ramon Antonio Chavez and Herman Perez, all of whom will be charged with belonging to an illicit criminal group and collaborating “in the flight of the perpetrators of a crime.”

Cotto said that the murdered guard was a member of the Association of Independent Guards of Markets and Shopping Centers, made up of 177 security workers, 50 of whom work at three markets in San Salvador.

In the area where the shootout occurred, there are numerous shops and street vendors selling their wares, and three of the latter reportedly were killed in the gunfire.

The PNC chief did not provide further details about the incident, but he said that security had been “increased” in the capital’s Historic Center and its environs.

The shootout erupted on Wednesday between private security guards and gang members, killing six people.

Meanwhile, also on Wednesday, 10 more people were killed when at least five Barrio 18 gang members murdered four women and then were intercepted by police and killed as they tried to make their getaway. One other person died Thursday morning in the hospital, but authorities have not identified that person yet.

According to officials with the Public Security Ministry, the number of murders in El Salvador has fallen so far this year to less than 60 percent of the figure during the same period in 2016.

El Salvador has been beset by violence perpetrated by the Mara Salvatrucha (MS13), Barrio 18 and other smaller gangs, which have more than 600 cells around the country, and which the government blames for most of the country’s crime.

The Central American nation is considered to be one of the world’s most violent, with murder rates of 103 and 81.7 per 100,000 inhabitants in 2015 and 2016, respectively.