Hurricane Maria is now a Category 4 storm. It made landfall on Puerto Rico after slamming Dominica. The National Hurricane Center calls Maria "extremely dangerous." It has sustained winds near 155 mph. Rainfall in the Puerto Rico area is expected to cause life-threatening flash floods and mudslides. Isolated areas of Puerto Rico are expected to get up to 25 inches of rain. Read more: http://www.businessinsider.com/sai FACEBOOK: https://www.facebook.com/techinsider TWITTER: https://twitter.com/techinsider INSTAGRAM: https://www.instagram.com/tech_insider/