Editor’s note: This story has been updated to reflect additional fatalities from seven reported earlier, as per Chihuahua state police officials.

EL PASO, Texas (Border Report) – Eleven people are dead following a shooting at a clandestine horse track about 200 miles south of Juarez, Mexican authorities said.

Witnesses reported the armed attack around 7:45 p.m. on Sunday at a ranch in the farming community of El Sauz; five people died on the scene and two more perished overnight at hospitals, the Chihuahua Attorney General’s Office said in a statement on Monday.

Five adult males were found dead on the scene; 10 other men and women sustained gunshot wounds and six succumbed to their injuries late Sunday or early Monday, said Ana Antillon, a spokeswoman for the Chihuahua Public Safety Secretary.

Police recovered five vehicles, one motorcycle and a trailer with a horse from the scene. Hundreds of .223-caliber and 7.62mm bullet casings were also recovered, the AG’s Office said. That type of ammo is usually associated with AR-15 and AK-47 rifles.

Authorities on Monday declined to disclose a motive for the shooting but said no suspects were in custody. A Chihuahua state official told El Heraldo newspaper the horse track lacked permits and that its operators may be subject to a $5,000 fine.

This is the second massacre reported in Chihuahua – a state that borders Texas and New Mexico – in the past 10 days.

On Good Friday, five vehicles traveling on Mexico Highway 2 came under fire from gunmen through to be associated with La Linea drug cartel. Two Chihuahua state police officers, a Mexican immigration agent and three civilians were killed inside the vehicles which were later incinerated by the attackers.

Chihuahua police arrested seven people in the nearby town of Janos they said had links to organized crime, but a judge freed them last week.

In late March, gunmen killed 20 people at a clandestine cockfighting arena in the state of Michoacan. Mexican authorities told local media the attack came from a rival group targeting Jalisco New Generation Cartel leadership in the region.