If you want to know more about the tensions that led to this tragedy I suggest you read this article by border report, a website set up by the local NBC affiliate in El Paso, Texas to cover immigration news. They reported weeks ago about the tensions that were building up between local residents and migrants, including the harrasment of women by the migrants. https://www.google.com/amp/s/www.borderreport.com/immigration/border-crime/mass-migrant-crossing-attempt-was-senseless-irrational-act-mayor-says/amp/

They did more than ask for money, there were hundreds of police complaints made by women in Juarez of being sexually harrassment by this problematic group of migrants who were rounded up. The local government tried for weeks to get them off the streets and they refused any offer of shelter, they wanted to create chaos in Juarez to put pressure on US immigration authorities to let them cross