A woman who tried to save the life of a stabbed teenager as he bled to death told his mum she "did everything she could."The 19-year-old victim, named locally as Andre, was stabbed multiple times outside a low rise block of flats in Selsdon, south London, on Tuesday night.His mum, believed to be called Yemi Hughes, brought flowers to the murder scene along with other mourning relatives earlier today (WED).She was met by a woman in her 50s who tearfully hugged her. The woman said: "I tried everything. I'm so sorry. I was holding his hand and talking to him. In so sorry.