MEXICO CITY (AP) — Two raids by security forces have netted the largest seizures of methamphetamine precursor chemicals in Mexico’s history, federal officials announced Friday.

Agents seized 20 tons of chemicals used to produce methamphetamine at Manzanillo port in the Pacific coast state of Colima and 17 tons the border city of Nuevo Laredo, across from Laredo, Texas, Mexico’s federal Attorney General’s Office said in a news release.

The agency did not say when the raids took place and officials did not immediately return phone calls asking for more details.

Mexico is a leading producer of methamphetamine, according to the U.S. government.

The seizures are part of a national crackdown launched in 2006 against drug gangs. The cartels, under increasing pressure, have responded with unprecedented violence; more than 13,500 people have died in drug violence in 3 1/2 years.

Officials say most of the dead are traffickers killed in battles with rivals, but police, soldiers and even bystanders have died as well.

Police in the border city of Ciudad Juarez said Friday that stray bullets killed a 10-year-old girl playing in a city park when gunmen opened fire on a pickup truck, killinga 22-year-old woman inside.

A man and woman were being treated for gunshot wounds and another child was injured in Thursday’s attack, said Arturo Sandoval, spokesman for the state prosecutor’s office.

In other violence, a female police officer was shot and killed inside a city bus Thursday, said Jacinto Segura, a spokesman for Ciudad Juarez’s police department.

Ciudad Juarez, across from El Paso, Texas, is Mexico’s deadliest city with more than 1,700 killings so far this year.