Monday's avalanche killed one officer and 16 soldiers.
Seventeen people have been injured, out of which six have multiple fractures and are in critical condition, the spokesman added.
"I am hearing about the tragic death of army personnel in the avalanche," Defence Minister A K Antony said in a statement.
He expressed "deep anguish" in a condolence message to the families of the deceased and to the army units which lost its men.
Antony also urged the army and local authorities to expedite rescue operations and provide adequate medical aid to the injured.
Jammu and Kashmir Chief Minister Omar Abdullah said two army personnel were still missing and search operations would resume tomorrow morning.
Soon after receiving the news about the tragedy, Omar Abdullah despatched Minister of State for Tourism Nasir Aslam Wani to Gulmarg to personally oversee the rescue operations.
The Chief Minister also offered his condolences to the bereaved families, an official release said in Jammu.
No tourist or civilian was among the dead or trapped under the heaps of snow, it said.
So far, 70 people had been rescued from the area despite the heavy snowing hampering the operations.
Over 350 armymen had set up a winter warfare camp at the High Altitude Warfare School in Khilanmarg when a massive avalanche, accompanied by a loud roar, rolled down the slopes to engulf the training centre.
As the avalanche hit, 90 armymen were swept away or buried under the snow, rocks and mud.
Officials said there was little chance of any tourist being trapped as the avalanche was triggered at an altitude higher than the popular skiing slopes that dot Gulmarg.
As the report about the accident reached Gulmarg, the army swung into action and launched a rescue operation amid heavy snowfall.
The bodies of 17 soldiers were recovered while over a dozen others rescued. The dead included an officer, Lt Prateek, and 12 other ranks from the High Altitude Warfare School which is located at an altitude of 2,730 metres (9,000 feet).
Heavy snow blocked Kashmir’s main highway, the only road link to the rest of the country, for the third day on Monday. The inclement weather conditions forced the authorities to close the 300-km-long Srinagar-Jammu National Highway to vehicular traffic.
Reports of snowfall were received from Pahalgam, Sonamarg, Youmarg, and Aharbal areas.
Gulmarg and its adjoining areas have been experiencing heavy snowfall this season. The state government has appealed to the people to be cautious while moving in the avalanche-prone areas of the Valley.
The meteorological department has predicted more snowfall and rain for at least two more days.