the persons on the train were professional criminals.
though, killing a criminal is not justified, it has been done a lot of times in india.
even in gujarat, raju risaldar and lafit sheikh are two names who come to mind.
in punjab, at the height of militancy, a lot of people have been killed.
in mumbai, there have been a lot of encounters.
theoretically, it is nice to say that even criminals should not be killed, in a legal system like india's, it could be good riddance if used with proper care to see that real innocents are not killed.