Hurricane Irene started off as a tropical storm, but reached hurricane status when it hit Puerto Rico Monday morning.

It is now a category 1 hurricane.

Irene was moving west-northwest at about 12 miles per hour with maximum sustained winds near 75 miles per hour, and the center was approximately 25 miles west of the capital of San Juan, CBS reported.

In Puerto Rico, Irene flooded streets, knocked down trees, caused several rivers to overflow their banks, and left more than one million people without power, the Associated Press reported.

As a tropical storm, it had already caused power outages in the Virgin Islands.

It is next set to hit the Dominican Republic and Haiti. People are still living in tents in Haiti as a result of last year's earthquake.  

Irene may also hit Florida, Georgia and the Carolinas, the BBC reported.