At least seven Maoists have been killed in an ongoing operation to flush them out while four others surrendered before the police in Malkangiri district, an official said Saturday."The 'Operation All Out' jointly launched by the Greyhound unit of Andhra Pradesh police, the special operation group and district voluntary forces of the Odisha Police, the Border Security Force and the Central Reserve Police Force have killed seven Maoists so far, while four surrendered before the police Saturday," Inspector General (south-western range) Yashwant Jethwa told media persons in Malkangiri. Jethwa said that of the four Maoists who surrendered, three were women. The security personnel of Andhra Pradesh and Odisha launched the operation Jan 5 along the border of the two states to destroy Maoist camps.