HOUSTON, Texas (KTRK) -- A woman was shot to death in northeast Houston late Sunday night, and police say a possible love triangle may be to blame.Police say a 20-year-old woman was outside her ex-boyfriend's house in the 7000 block of Sayers Street waiting for him to come home around 8 p.m. Sunday night.Investigators say she got angry when she saw her ex with another woman in his car.Police say she grabbed a shovel and went after her ex. He was able to get the shovel from her.That's when investigators say she went back to her car and grabbed a knife and went after the 22-year-old woman in her ex-boyfriend's car.Investigators say that woman got a gun from the glove box and shot the ex-girlfriend in the head.She was pronounced dead at the scene.The shooter and the ex-boyfriend were interviewed by investigators. They have not been arrested.Houston police say the case will be referred to a Harris County grand jury.The name of the woman who was killed has not been released.