"Five people were taken to a speciality hospital in the Kanpur town have died. One person has been declared dead at the spot. We are trying to get those trapped out as soon as possible," said Anand Kumar Singh, a senior officer in Kanpur. Out of those dead, five were migrant workers from Bihar, he added.
At least 25 people were inside the building at the time of the incident. Eleven people, including farmers and cold storage staff, have been rescued from the rubble.
Ten ambulances were rushed to the spot. JCB and cutters were also present on spot. The fire department is carrying out the rescue and relief operations, SP (Rural) Rajesh Kumar said.
The gas leak started at the Katiyar Cold Storage in the afternoon. In the resulting explosion, the roof of the structure collapsed, said Mr Kumar. The Army's help has also been requested.
The hospital staff has also been put on alert as the number of those injured is expected to rise.
The farmers had arrived at the cold storage building at Shivrajpur, 40 kilometers away from Kanpur, to stock potato harvest. The cold storage owner and his son are still trapped in the rubble.
Officials said the building apparently came down after a gas leak in the chiller plant led to an explosion.
According to officials present on scene, there was leakage of ammonia gas and masks have been requisitioned from Kanpur city so that rescue operations can be taken up at the earliest.
According to latest reports, those injured are now out of danger.