BENGHAZHI (Reuters) - A powerful Mediterranean storm swept through eastern Libya, damaging houses and roads and killing at least three people, government sources and witnesses said on Monday. Authorities declared a state of extreme emergency, closing schools and stores and imposing a curfew as the storm hit on Sunday and Monday. ?in Libya including Ras Lanuf, Zueitina, Brega and Es Sidra were closed from Saturday evening for three days, two oil engineers told Reuters. The United Nations in Libya said it was following the storm closely and would "provide urgent relief assistance in support of response efforts at local and national levels". (Reporting by Ayman Werfali in Benghazi and Ahmed Elumami in Tripli, Writing by Tarek Amara in Tunis, Editing by Nick Macfie)