An 18-year-old youth was behind bars Saturday, charged with fatally stabbing an ex-girlfriend in a Los Angeles high school cafeteria, authorities said. Abraham Lopez was being held without bail in the slaying of Cindy Santana, 17, and could have an initial court appearance on a murder charge Monday, Los Angeles' KABC-TV reported. The fatal attack occurred Friday morning at South East High School in front of dozens of students and Santana died later in the day at a hospital, the TV station said. Witnesses said Lopez punched and choked Santana during a fight during their lunch hour and then pulled a knife. Another student and a school employee were cut when they tried to subdue the 250-pound Lopez but were expected to recover, school officials said. The attack led to a lockdown at the school.