Los Angeles police launched a full-scale manhunt Thursday for a dismissed officer believed to have killed three people in the US state of California including another cop. Christopher Jordan Dorner had posted a chilling online warning about "terminating" the life of a colleague he blamed for his dismissal, and threatening other police and their families. The LA Police Department (LAPD) said it was increasing protection for a number of people named in an online manifesto by Dorner, a 33-year-old US Navy reservist who was described as "armed and extremely dangerous."