Moses facilitated it at least twice (Leviticus 24:10-16, Numbers 15:32-36).
Execution can easily be done in an instant, if it meant taking the life of another human being.
What do you think is meant by,
"Let the dead bury their dead." ?
Put them outside the camp, for a limited time or indefinately.
"Jew" has become a curse word,
but the correct description is,
"Sons and daighters of Israel"
What do you say about a brother executing a brother,
or a sister?
Perhaps it was the rage of the mob.
Perhaps since they had recently handed Jesus over to be crucified and that hadn't contained his disciples's message, they decided to try something different.