Three security personnel and estimated 12 Maoists have been killed in an ongoing encounter for the last three days in the Saranda forest range of Jharkhand's West Singhbhum district.Jharkhand Director General of Police Neyaz Ahmad said that ten to 12 Maoists have been killed since Saturday, with some of the bodies of the naxals yet to be found.Meanwhile, the Maoists blew up a hostel and panchayat bhawan at nearby Anandpur and triggered three land mine blasts in the Tirilposhi jungle this morning. The security personnel has already smashed two training camps of the Maoists, a bunker and seized weapons and five grenades.Around 5,000 security personnel comprising state police of Jharkhand and Orissa and Central Reserve Police Force (CRPF) personnel began a combing operation in the Saranda jungles Saturday where 400 Maoists were reportedly present. The operation was led by a Deputy Inspector General of police of Kolhan Range Naveen Kumar Singh. Six SP level officers are taking part in the operation, in which three helicopters were deployed for surveillance and airlifting of injured security personnel.