Timer devices could have been used to detonate three low-intensity bombs on Tuesday evening in a crowded shopping area of Gorakhpur, a senior police official said on Wednesday.

A Special Task Force team from Lucknow has also rushed to Gorakhpur for further investigation.

Senior Superintendent of Police R K Rai said timer devices could have been used to set off the three blasts.

The bombs kept in tiffin boxes and tied to cycles went off at five minutes' interval after 7 pm -- near Baldev Plaza, Ganesh crossing and and Jalkal building in the busy Golghar area, he said.

Security has been beefed up in sensitive areas of Gorakhpur, which recently witnessed communal violence. All exit points from Gorakhpur have been sealed.

Security around the famous Gorakhnath temple, which has been on the hit list of terrorists, has also been tightened.

Police are also investigating whether the blasts have any link with the recovery of 10 kilograms of explosives and 20 litres of ammonium nitrate from Faizabad railway station in the wee hours on Wednesday.

Meanwhile, five persons, who were injured in the blasts, are being treated at the district hospital in Gorakhpur and have been declared to be out of danger.

The injured have been identified as Rajesh Kumar (32), Santosh Singh (35), Sanjay Rai (35), Ganesh (41) and Rameshwar Patel (30).