An American mother of four was killed and her younger sister was wounded during a mass shooting in Mexico Sunday night, her family told CBS Chicago. The woman, 36-year-old Melissa Silva, and her sister had traveled to Mexico to visit family, when gunmen burst into a gathering, killing 20 people. Her sister was shot - but survived.

Melissa's brother, Alex Silva, told CBS Chicago that he and his family are devastated.

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

Melissa grew up in the western Chicago suburb of Warrenville, but moved to Watsonville, California. She was one of 20 people killed at a venue used to host cockfights in the town of Las Tinajas, Michoacan state in Mexico Sunday night.

"I get a phone call from a friend out here telling that they heard gunshots and that it came from that place, and two minutes later, my mom calls me that she had just arrived to the place and she saw my oldest sister laying on the floor," Alex Silva told CBS Chicago.

His younger sister, 16-year-old Arleth Silva, was also at the event and was shot twice in the leg and once in the lung.

"It looked like she was trying to walk or go help my older sister, and when she tried, she got hit," Alex Silva said.

Alex flew to Mexico to bring his wounded sister back home to Warrenville. He said Melissa will be buried in Mexico. The family has set up a GoFundMe page to help with funeral and hospital expenses.

"She was just a hardworking mom," he said. "She was single. She provided for her kids - anything they needed. She'd give them anything."

Michoacan and neighboring Guanajuato are two of Mexico's most violent states, due to turf wars between rival gangs involved in drug trafficking and other illegal activities — including trade in stolen fuel.

Earlier this month, gunmen killed the mayor of a town in Michoacan. Aguililla Mayor Cesar Valencia was shot dead by unknown attackers while traveling in a city hall vehicle near a soccer field in the town, officials said.

(editor：)