By Scott Vincent and Sarah Morland (Reuters) -Residents in the Bahamas and Turks and Caicos braced on Monday for Hurricane Erin, a dangerous Category 4 storm and the first of the Atlantic season, after it strengthened over the weekend while sweeping past Caribbean islands.

After weakening a bit, Erin continues to strengthen and grow. A tropical wave could become the next depression or storm.

Hurricane Erin's outer bands were beginning to lash the southeast Bahamas and the Turks and Caicos Islands early Monday after regaining Category 4 strength overnight.

A 63-year-old American man, who was attacked by a shark while spearfishing near Big Grand Cay, The Bahamas, has been airlifted to the United States (US) for medical treatment. A statement from the Royal Bahamas Police Force did not identify the American national,

Police said "a 63-year-old male resident of the USA was spearfishing when he was attacked by a shark, sustaining severe injuries."