Russia is observing a national day of mourning in memory of at least 177 people killed in the past few days in three separate disasters - a mine explosion, a nursing home fire and a plane crash. Lisa McAdams in Moscow reports.

Flags are flying at half-mast today across Russia, as the nation struggles to come to terms with the large loss of life, which investigators say could have been avoided, if proper safety regulations had been addressed.

In Kemerovo, in Central Siberia, the search is still on for three coal miners missing following Monday's methane gas explosion that killed more than 100 people. It is Russia's worst mining disaster since the collapse of the Soviet Union.

Russian Emergency Situations Minister Sergei Shoigu says the massive search and rescue effort could take up to three more days to complete.

Families who lost loved ones in the mines are preparing for the first funerals, Thursday. They have been promised roughly $25,000 each by the Russian government.

Kemerovo's Regional Governor Aman Tuleyev says the lump sum payments will be dispersed in the next nine days.

Russians are also pausing to remember 63 elderly patients of a nursing home who died in a fire in Russia's Southern Krasnodar region. The mostly bed-ridden patients were asleep when the fire broke out in the early hours, Tuesday.

Days before that, a plane crash in Samara took six lives.