San Juan - Some 70 000 people were ordered to evacuate their homes on Friday after a rain-swollen dam in Puerto Rico failed in the latest disaster caused by Hurricane Maria.With the death toll from the storm at 33 across the Caribbean, the National Weather Service office in capital San Juan issued a flash flood warning for people living along the Guajataca River and said the 1920s earthen dam was in danger of collapsing altogether."All areas surrounding the Guajataca River should evacuate NOW. Their lives are in DANGER!" the service said in a tweet. Flooding has already begun downstream, it said.Shortly thereafter, Governor Ricardo Rossello issued an order for some 70 000 people living in the area in the northwest of the island to get out.According to the newspaper El Vocero, Public Safety Secretary Hector Pesquera said a drain that normally releases a stream of water from the dam in a controlled fashion had broken.Dangerous floodsInstead the busted drain sent water gushing down a ramp-style conduit, eventually washing away huge chunks of soil from the grassy green slope of the dam, according to video on the WeatherNation website.However the flash flood warning was only due to last until 06:00 GMT, the weather service said, suggesting that the river waters were receding.Puerto Rico was already battling dangerous floods after Hurricane Maria ravaged the island early on Wednesday. Rescuers raced against time to reach trapped residents.Rossello has called Maria the most devastating storm in a century after it destroyed the US territory's electricity and telecommunications infrastructure.Rossello told CNN the island is lacking communications and the preliminary assessment at this point is 13 fatalities."Right now our efforts are to make sure we have everybody safe, that we can rescue people. Our efforts have already produced almost 700 rescues so we're clearly focused on that."The National Hurricane Center said some areas in Puerto Rico could see 100cm of rain from Maria, and Rossello warned of dangerous mudslides brought on by the deluge."We have a lot of flooding, we have reports of complete devastation of vulnerable housing. Of course it's still raining over here."Maria has been blamed for at least 33 deaths, including 15 in Dominica, three in Haiti and two in Guadeloupe.