Prime Minister Manmohan Singh spoke to Sikkim Chief Minister Pawan Chamling immediately after the quake and offered all possible help.
He directed Cabinet Secretary Ajit Seth to urgently convene a meeting of the Crisis Management Group, which took stock of the situation and decided on a series of steps.
After the meeting, Seth said that two IAF planes --C-130J with four teams of National Disaster Response Force (NDRF) -- have been sent for rescue and relief operations in Sikkim. He said five more teams of NDRF are being rushed from Kolkata.
Army units have also been mobilised and field hospitals have been activated in Sikkim, he said.
The Border Roads Organisation (BRO) has also been mobilised for restoring normal traffic on NH-31A which connects Sikkim with rest of the country.
"The Prime Minister himself is monitoring the developments connected to the quake," Seth said after the meeting, which was attended by Secretaries of Defence, Home, Health and Information and Broadcasting, among others.
The Cabinet Secretary said the meeting discussed ways in which help could be provided to the quake-hit Sikkim in the wake of the earthquake.
"The Central Government will do everything that is necessary."
More updates on Sikkim earthquake:
# Road from Pegong to Chungthang tehsil washed away due to landslide.
# NDRF personnel are waiting for the highway to be cleared.
# Sikkim govt confirms 18 deaths. Rescue team of state has reached Mangan area of north Sikkim but they are yet to get input from Chungthang.
# Big landslides all over NH 31A - the lifeline of Sikkim. NDRF forces are still stranded in Siliguri.
# A herculean rescue operation begins as NDRF and Army battalions reach Sikkim.
# Missing vehicle including Army personnel found, all safe: Report
# 10 army Combat Engineers Columns deployed for opening major roadblocks on Siliguri-Gangtok.