Having heard explosion or having found out that the house starts to lose stability, try to leave it as fast as possible. If possible, take your documents and money. It is desirable to not use the lift; come downstairs, if the staircase remains intact. Do not panic, but act quickly.
Having left a building, move away from walls which can collapse. Rules of behavior are the same as at earthquake: disconnect immediately gas and electricity, open an entrance door, choose a safe place near main walls, or simply hide under a bed or under a table.
If you are trapped under debris, do not panic - help will necessarily come. Try to choose a safe place or a convenient position (if conditions allow it), learn whether there is somebody beside you and the main thing - try to inform on yourself the people outside. Knock your boots against the wall, shout, beat a brick against a brick or against a metal pipe, dial any familiar number on your mobile phone.