Updated

An American mother of four was reportedly among 20 people killed in a shooting massacre at a cockfighting venue in Mexico

Melissa Silva was killed, and her 16-year-old sister, Arleth Silva, was wounded after gunmen opened fire at the venue in the western state of Michoacan on Sunday, according to a report.  

An agent of the Michoacan Attorney General's office places a lock and chain on a gate at a clandestine cockfighting ring following the killing of at least 20 people on Sunday night during an attack, authorities said, in Zinapecuaro, Mexico March 28, 2022.

An agent of the Michoacan Attorney General's office places a lock and chain on a gate at a clandestine cockfighting ring following the killing of at least 20 people on Sunday night during an attack, authorities said, in Zinapecuaro, Mexico March 28, 2022. (REUTERS/Stringer)

Arleth Silva remains in critical condition at a hospital in Mexico. Her family said she was shot three times – once in the lungs and twice in the leg. Three others were wounded in the shooting. 

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On a GoFundMe page set up to help cover funeral and hospital expenses, the family said Melissa Silva leaves behind four kids, three of whom are under the age of 18. 

Army officers and Michoacan state prosecutors inspect the cockfighting site "El Paraiso," or Paradise in Zinapecuaro, Mexico, Monday, March 28, 2022. 

Army officers and Michoacan state prosecutors inspect the cockfighting site "El Paraiso," or Paradise in Zinapecuaro, Mexico, Monday, March 28, 2022.  (AP Photo/Armando Solis)

Melissa's brother, Alex Silva, told WBBM-TV the family is devastated. 

"I went crazy for a couple of minutes," he told the station. "I couldn't believe it." 

Federal officials said the gunmen appeared to have planned the attack, entering the venue inside a stolen truck owned by a snack food company and using a bus to block those inside from escaping or calling for help. 

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"The snack food company truck arrived, and several armed people in camouflage clothing got out," a prosecutors' statement said. "At the same moment, a bus that was outside the building was used as a blockade."

Soldiers patrol the cockfighting site "El Paraiso," or Paradise in Zinapecuaro, Mexico, Monday, March 28, 2022. 

Soldiers patrol the cockfighting site "El Paraiso," or Paradise in Zinapecuaro, Mexico, Monday, March 28, 2022.  (AP Photo/Armando Solis)

Prosecutors said one vehicle that appeared to belong to a victim had stickers with the logo of a criminal gang, adding that drug cartels and other criminal gangs had been fighting in the area.

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"There are indications that the attack involved a confrontation between criminal groups," the federal Public Safety Department said in a statement. It said a team of federal investigators had been sent to the scene.

Fox News’ Stephen Sorace and The Associated Press contributed to this report