The authorities across the US state of Texas continued on Monday to rescue people stranded by devastating, historic flooding left in the wake of Hurricane Harvey, even as forecasters warned of looming rain, rising rivers and floodwaters that would still swallow more streets and neighbourhoods. Officials warned that the danger was far from over, saying that flooding in Texas was unlikely to recede quickly and that the storm will force more than 30,000 people from their homes, the Washington Post reported. A record 30 inches of rainfall already fell on Houston, the country's fourth-largest city and a sprawling metropolitan area, turning roads into rivers. Although five people were reported dead and dozens injured in the hurricane, the full toll of Harvey's destruction remained unclear, said the report. The city faced dire circumstances and the National Weather Service (NWS) forecast more heavy rainfall. Up to 2,000 people had been rescued on Sunday in and around the city. President Donald Trump on Monday approved an emergency declaration for neighbouring Louisiana, where forecasts called for as much as two feet of rainfall in some areas. The NWS said conditions are "unprecedented". A "flash flood emergency" was in force across the Houston area, with travel near impossible. More than 82,000 homes were without electricity in the Houston area by Sunday night as airports shuttered and hospitals planned evacuations. The authorities ordered more than 50,000 people to leave parts of Fort Bend County, about 35 miles southwest of Houston, as the Brazos River was set to crest at a record high of 59 feet this week, 14 feet above its flood stage, CNN reported. Also, the US military released water from two major reservoirs earlier than planned to protect central Houston, a move that could itself flood several thousands homes. Residents nearby were told to evacuate in case of danger. Authorities had fielded scores of calls for help throughout the night from people stranded by water. Police in Houston dispatched officers on boats that were sent through streets where the floodwater reached the pumps at gas stations. Families scrambled to get out of their fast-flooding homes in and around the city. Rescuers in fishing boats, huge dump trucks and even front-end loaders battled driving rains to move people to shelter. Thousands of rescue missions were launched across Texas, and Governor Greg Abbott said that more than 3,000 national and state guard troops had been deployed to assist with relief efforts. An additional 1,000 National Guard members were expected be sent to Houston on Monday, Abbott said. The White House said Trump plans to visit parts of the state on Tuesday. Meanwhile, Indian External Affairs Minister Sushma Swaraj posted a tweet saying 200 Indian students were "marooned" in floods. She also said two Indian students were in the intensive care unit (ICU) of a hospital. Harvey made landfall as a category-four hurricane late on Friday. It was later downgraded to a tropical storm. The damage bill of Hurricane Harvey is already drawing comparisons to Hurricane Katrina in 2005, which caused $108 billion of losses (including $80 billion of insured losses).