I categorize my sister as stupid.

context before the story:

-I don't live in the United States -Here it's normal to eat handmade tortillas for some meals -The tortillas are made on a stove with a griddle; this stove is portable and has its own separate gas tank for cooking -Fireworks are sold to any idiot with money, regardless of age.

people involved: -My mom: 51 years old -My sister: 17 years old -the woman who makes the tortillas, I'll call her "E" -the tortilla lady's daughter: 4 years old, I'll car her G

All of this is important to understand the stupid thing my sister did.

This just happened literally, I was watching MasterChef Argentina on TV (I'm not Argentinian but I like the reality show), the thing is that my mom quickly scared me because she came in crying, I got up to see if she was having a breakdown or if my sister had said something to her (it happens quite often), Then I saw my mom's arm and it was purple, swollen, and bleeding. I got scared and quickly grabbed everything I could to clean it up. Once my mom was sober and I calmed down, she told me what happened. My mom often hangs out with the lady who makes tortillas (E) on my block because they are friends. While my mom was going to talk to E, she saw my sister and her friends setting off strange fireworks. My mom doesn't approve of this, but my sister doesn't pay any attention to her My mom told her to at least do it away from people and cars. My mom was calm. E and her daughter G were there. G was watching her mom while E put away the tortilla stove so she could go home. While E was removing the gas tank to put it away, my mom saw out of the corner of her eye how my sister threw a mini bomb that was releasing sparks, The bomb exploded near my mom and sparks fell on E. She dodged, but the gas tank released a huge burst of flame, which scared E because she thought her daughter might have been burned since she started crying. Luckily, it was just a scare, and E was able to put out the fire. I was there, so I don't know how happened, the thing is, even with all that, my sister doesn't care. She kept setting off fireworks and said that if E said anything to her, she was going to fight him. I'm literally about to yell at her for being so stupid.