Why did Gandhiji withdraw the Non-Cooperation Movement?

A procession of about 3000 peasants marched to the police station at Chauri Chaura village in Uttar Pradesh on February 5,1922 to protest against the police officer who had beaten some volunteers picketing a liquor shop. The police fired at the peasants. In retaliation, they set the nearby police station on fire, killing 22 policemen. Gandhiji was shocked by the incident and he decided to withdraw the Non-Cooperation Movement on February 12, 1922.