They said the bicyclist became upset, and he and a group of people tried to fight Torres and her friend.
Click here to watch newly released video of that fight.
Investigators said Torres' friend got involved in the fight, which she tried to break up before driving them away.
Officials said Torres noticed that her cellphone was missing, so she returned to the gas station, where someone told her that one of the people in the group had stolen it.
Detectives said Torres circled the block in search of her cellphone, and she encountered some of the people involved in the fight.
They said a gunman shot toward Torres' friend but hit her in the neck.
During a Wednesday morning news conference, Torres' mother, Elizabeth Torres, urged anyone with information about her daughter's death to call detectives.
"I go every other day to the site and pass out flyers, hoping that I can find someone (who) will have pity, someone who has mercy and (will) give us information about this," she said. "This will not bring Kayshla back, but at least it will give us some type of closure."