SAN JUAN, Puerto Rico -- Tropical Storm Irene barreled toward Puerto Rico late Sunday after hitting St. Croix, packing heavy rains and winds that closed airports and flooded low-lying areas in the Leeward Islands.

The fast-moving storm, moving west-northwest at roughly 15 mph was taking an unpredictable path that left people in the islands of the U.S. Caribbean anxious about the winds and rain to come. Its maximum sustained winds late Sunday night were 70 mph.

On its current forecast track, Irene was expected to pass over Puerto Rico late Sunday and over Hispaniola, the island shared by the Dominican Republic and Haiti, on Monday or Monday night. Nearly 600,000 people in Haiti still live without shelter after last year's earthquake.

Puerto Rico's main airport was swamped with people, the usual Sunday crowds combined with people rushing to get off the island before the storm or stranded because flights to a number of other islands had been canceled.