Melissa Silva, a California mother of four, was killed in a mass shooting at a Mexican cockfight Sunday night. The shooting left 20 dead and several others injured. Multiple gunmen stormed the El Paraiso venue in the town of Las Tinajas, Mexico, and opened fire, striking Melissa, 36, and her younger sister, 16-year-old Arleth Silva.

Arleth was shot twice in the leg and once through her lung, according to the family, but is reportedly recovering in critical condition at a nearby ICU. Her sister, Melissa, did not make it. Melissa Silva grew up in Chicago and ultimately moved to California. She was on vacation in Mexico visiting her sister when the incident occurred.

According to local outlets in the Michoacan state, drug cartels have ramped up business in the area, and allegedly targeted the venue in Sunday night’s mass shooting.

Melissa Silva and her sister Arleth Silva, victims of the mass shooting in Mexico. Arleth is in critical condition
Melissa Silva and her sister Arleth Silva, victims of the mass shooting in Mexico. Arleth is in critical condition. Photo Credit: GoFundMe

Though a motive for the attack has not yet been found, Mexican officials stated that gunmen dressed in military gear entered the El Paraiso venue with automatic guns and opened fire in what “appeared to be a choreographed attack.”

“There are indications that the attack involved a confrontation between criminal groups,” the Mexican Public Safety Department announced.

Mexico’s president, Andres Manuel Lopez Obrador, also announced that the country would investigate the killings and blamed organized crime and gangs. “It was a massacre of one group by another,” he stated during a press conference.

Nineteen people, including 16 men and three women, died at the scene, with another victim dying on their way to the local hospital.

Those responsible for the shooting have yet to be captured, according to Michoacan state police, but 15 vehicles were seized – along with over 100 shell casings – that were set up in the roads outside the venue to block people from escaping.

In recent months, the drug cartels have been blamed for increasing violence and targeted killings in the Mexican town, which authorities blame on a new fight over turf.

Earlier this month, Cesar Valencia, the mayor of Aguililla, was fatally shot and killed. Just before his assassination, a mass shooting in San Jose de Gracia killed 17 people attending a funeral in broad daylight. According to The Independent, the gunmen lined their victims up along a wall before executing them and later took the bodies with them as they fled the scene.

Michoacan’s secretary of public security released a statement on Sunday night’s latest mass shooting at the cockfighting venue, vowing to stop “those responsible for the violent acts.”

Alex Silva, Melissa and Arleth’s brother, told ABC News that he plans on traveling to the small town in Mexico to bury his siblings. He told local reporters that he “went crazy for a couple of minutes” when he heard his Melissa was dead and Arleth was in critical condition.

“I couldn’t believe it,” he explained. “She had just arrived to the place and she saw my oldest sister laying on the floor.”

Arleth Silva, Melissa Silva's sister, is in critical condition at a local Mexican ICU
Arleth Silva, Melissa Silva’s sister, is in critical condition at a local Mexican ICU. Photo Credit: Instagram

He described Melissa Silva as a “hardworking” single mother, saying that “she provided for her kids – anything they needed. She’d give them anything.”

According to a GoFundMe page, her four children were 10, 12, 17, and 18 years old. The fundraiser raised over $14,000 as of Thursday morning.

“I am so sorry that this happened. My heart goes out to Alex and the rest of his family, parents and siblings. No one should ever have to go through this,” one donator commented on the page. “Sending you positive thoughts, prayers, and hoping you all take the time to grieve and heal from this tragedy.”