Maoists triggered about a dozen explosions in the wee hours on Thursday, blowing up railway tracks and at least four government buildings in Orissa’s Sundargarh district.

The Maoists have called for a 24-hour shut-down in the district today to demand release of 30 people, who were arrested on the suspicion that were naxalites.

The rebels blasted railway tracks at around seven places between Bimlagarh and Patangi, police said.

The ultras also blew up an abandoned police station building at Kalta, another building where a CRPF camp was functioning earlier, a community centre and office building of CITU, police said adding they also set afire a truck.

Train services between Rourkela and Barsuan have been completely disrupted due to the blasts.

The route is used mainly for transportation of raw materials to Rourkela Steel Plant (RSP).

Train services on the route had been disrupted for the last three days due to ongoing agitation by tribals demanding release of the 30 people branded as Maoists.

There was no report about any casualty in the attacks carried out by the ultras.