Maoists today blew up railway tracks at two places in Jharkhand, disrupting train services besides bombing a school on the third day of their 72-hour shutdown in five naxal-hit states to protest the Centre's proposed offensive against them.

The incidents came hours ahead of the meeting of chief ministers of naxal-affected states convened by Home Minister P Chidambaram in Kolkata.

Maoists blew up tracks under Nimiaghat police station in Giridh district in the wee hours, Superintendent of Police Ravi Kant Dhan said.

"Trains on this section have been stopped on both up and down lines," Parasnath station superintendent Mritunjaya Kumar said, adding a couple of deafening explosions were heard around 2 am.

The Maoists also triggered blasts on tracks between Karmabad and Choudhary Bandh railway stations in Giridih district, blowing up a three-metre stretch of railway track, the police said.

Dhanbad Divisional Railway Manager, S Upadhaya, said several trains have been stopped at Gaya and Mughalsarai following the damage to the tracks.

Yesterday, Maoists blew up railway tracks in Orissa and Bihar.

In Khunti district, Maoists blew up the Project High School late last night at Sodeh village, Superintendent of Police A B Minz said today.

The Maoists had on Sunday called the bandh in Bihar, Jharkhand, Orissa, West Bengal and Chhattisgarh to protest the proposed all-out offensive against them by the Centre.