Extremely severe cyclone ‘Amphan’ has killed at least 12 persons and ravaged Kolkata and several parts of West Bengal as it left behind a trail of destruction by uprooting trees, destroying thousands of homes and swamping low-lying areas of the state. While a man and a woman were killed when trees came crashing down on them in North 24 Parganas district, a 13-year-old girl died in a similar incident in adjoining Howrah, officials said.