Police in the Indian state of West Bengal say several bombs have been found in the state's second largest town of Siliguri.
The bombs, which were set to go off at 10am local time, were placed near oil dumps and petrol pumps.
If all the bombs had exploded, police say they would have set off huge fires in key areas of the city.
They say two policemen from the state's bomb disposal squad have been arrested and are being questioned.
Officials say the arrested policemen, both of the rank of constable, "have confessed to planting the bombs".
The Inspector General of Police for North Bengal, KL Meena, said: "Two bombs were placed at petrol pumps and the fires from them would have destroyed the bridge on river Mahananda, which links Siliguri with the rest of the state."
Another set of bombs, Mr Meena said, was placed near the Indian Oil Corporation's storage dumps near the railway station.
"An explosion here would have caused huge fires and that could have engulfed several trains too," he said.
Senior police officials in West Bengal say they suspect the two arrested policemen have links with separatist groups active in north Bengal and the neighbouring state of Assam.