The Special Task Force of Uttar Police has been handed over the investigation into the serial blasts, which rocked Gorakhpur in quick succession on Tuesday evening.

Sources in the police headquarters said senior STF officials have reached Gorakhpur to begin the probe. Officials have instructed all district magistrates to maintain law and order, and take stringent action against rumour-mongers.

At least six people were severely wounded in the three blasts, which took place in the space of five minutes, at a petrol pump, Baldev Plaza market and Hotel York in the district.

Meanwhile, the international border that the state shares with Nepal and all other sensitive places in the state have been put on high alert.

Security has been strengthened at all important religious and historical monuments, including Ayodhya, Sri Krishna Janmabhoomi, Mathura and Taj Mahal in Agra.

Besides, security has been tightened at all railways stations and bus terminals in the state.