Fifteen persons were killed and over 300 injured in a severe cyclonic storm that lashed West Bengal's south 24 Parganas and east Midnapore districts in the early hours on Wednesday as an alert was sounded in coastal districts with heavy rains forecast in the next 48 hours.

The storm, caused by the formation of a well-marked low pressure area over the northwest bay and adjoining coastal north Orissa and gangetic West Bengal, left a trail of destruction in the two districts, razing thousands of dwellings, trees, power and telephones poles and damaging standing paddy.

The Sunderbans in south 24 Parganas district bore the brunt of the storm with 10 blocks seriously affected, prompting Sunderbans Development Minister Kanti Ganguly to rush with a rescue and relief team on Wednesday morning.

State Finance Minister Asim Dasgupta and Relief Minister Murtaza Hussain told reporters the toll may cross 20 adding, that over 13,000 dwellings collapsed in the storm.

The state government has sanctioned Rs 3 crore for relief and rehabilitation in south 24 Parganas and Rs 1.50 crore for east Midnapore district in consultation with Chief Minister Buddhadeb Bhattacharjee, the finance minister said.