Drug cartels across Mexico are increasingly turning to car bombs, explosives-laden drones and improvised explosive devices, a trend that could further strain Mexico’s already tense relationship with U.S. President Donald Trump, who has repeatedly threatened military action against the cartels.

The latest incident occurred Sunday night outside a police station in Ojocaliente, a town in the north-central state of Zacatecas, about 360 miles (580 km) northwest of Mexico City. No one was killed, but the explosion of 200 kilograms (440 pounds) of explosives injured 11 people and damaged more than 60 homes in the city center, Mexico’s security chief Omar García Harfuch said Friday during a visit to Zacatecas with President Claudia Sheinbaum.

So far this year, Zacatecas has recorded 23 attacks involving explosives, including six involving cars or motorcycles packed with explosives, state Attorney General Cristian Paul Camacho said.

The Jalisco New Generation Cartel, or CJNG, and the Sinaloa Cartel have fought for years over control of Zacatecas.

Here’s what to know about why the car bombings are raising concern in Mexico, even though their scale remains far below the violence seen in countries such as Colombia.