Pogrom via Yiddish from Russian: destruction, from po- like + grom thunder.
"After the war around 150 Jews left their hidings and returned to Kielce. They found a place in their former parish hall, waiting for a possibility to emigrate to Palestine. In June 1946 they were accused of having committed a ritual murder on a missing Polish boy. On 1 July 1946 a furious crowd gathered round the building and on 4 July 1946 they killed 42 Jews."
Sources: http://www.holocaustresearchproject.org/ & http://www.thefreedictionary.com/