Two suspects have been arrested in the investigation into the improvised bomb attack that killed six people and injured 15 others last Tuesday near Guadalajara, in western Mexico, prosecutors said Monday.

The suspects will be charged “within the next few hours” for murder, causing serious bodily harm and assault on the authority, Jalisco state prosecutor Joaquin Mendes said during a press conference.

Four police officers and two civilians were killed when improvised explosive devices detonated as a convoy of prosecutors and police passed through Tlachomulco, a community notorious for secret mass graves of the disappeared.

Although relatively rare in the history of Mexico’s drug-trafficking gangs, attacks with explosives are on the rise, President Andres Manuel Lopez Obrador acknowledged last week.

“We are constantly confiscating explosives,” he said, refusing, however, to talk about terrorism, a phenomenon connected a priori “with political ideologies and fanaticism.”

In late June, a member of the National Guard was killed and others were injured in a car bomb explosion in the state of Guanajuato.

The state of Jalisco has the highest number of disappearances in all of Mexico, about 15,000 since 1962, out of a total of 111,000-plus in the territory, according to official figures.

This state is the cradle and stronghold of the Nea Genia tou Jalisco (KNGH) cartel, which is considered extremely cruel and is characterized as one of the two strongest gangs in the country, along with the Sinaloa cartel.

In Mexico, there have been some 350,000 recorded murders and tens of thousands of reported disappearances, crimes that the country’s authorities attribute mostly to gangs, since the so-called “war” on drugs began, the highly controversial operation to crack down on cartels with the deployment of the military inside the country in December 2006.