WASHINGTON-Hurricane Gaston picked up strength Sunday as it swirled in the Atlantic east of Bermuda, the US National Hurricane Center (NHC) reported. Gaston has sustained maximum winds of 90 miles (150 kilometers) per hour, the Miami-based NHC said in its 0900 GMT bulletin. The center of Gaston was located 620 miles east of Bermuda and was moving towards the northwest at a speed of six miles per hour. Gaston became the third named hurricane of the Atlantic season on Thursday, but quickly weakened to a tropical storm.