Bhopal: Madhya Pradesh police on Tuesday sounded an alert in Naxal-affected districts of Balaghat and Singrauli in the aftermath of a deadly Maoist attack in neighbouring Chhattisgarh. The alert, issued by Director General of Police (DGP) Nandan Dube, directed police personnel in the two districts to increase vigil and foil any attempt by the extremists to disturb peace, police sources said. Naxals today ambushed a security team, killing 16 people, 11 of them CRPF personnel, in Sukma district of Chhattisgarh.