1. Critics say had the commandos arrived within the few hours if not minutes, it would have saved many more innocent lives.
how about.. more innocent lives had would been saved (is this correct)
2. Indeed, before NSG commandos arrived from Delhi, the Marine Commando from the Navy had took the control of situation as they swung into action within few minutes, which led to save many lives
3. I am planning to welcome the New Year by offering the pray at the stroke of mid-night for all the brave policemen and innocent people, who lost their lives to the on slaughter of terrorists.
4. Some suggested that the best way to celebrate the New Year is to sing national anthem rather than dancing to the tunes of film numbers.
The phrase "within a few minutes" is generally used this way:
Within a few minutes of A happening, B happened.Immediately:
B happened within a few minutes of A happening.
B happened immediatly after A.