Harvey's havoc continued to pour down, three days after the storm rammed Texas as a Category 4 hurricane, unleashing a torrent of rain, turning streets into rivers, and leaving thousands of residents stranded in flooded homes.
Harvey, a tropical storm by Tuesday morning with its eye hovering over the Gulf of Mexico, could still dump up to 15 inches of rain on portions of southeastern Texas and southwestern Louisiana, including the saturated Houston area, where thousands have been rescued and many more still wait for help.
Headed east, the storm was due to dump more heavy rain across both states, worsening the "catastrophic and life-threatening" flooding situation, before making landfall again Wednesday morning, near the Texas-Louisiana border, according to CNN Weather Center.
Four people have died as a result of the catastrophic storm, and thousands of Texans are believed to have sat in darkness overnight Monday amid rising floodwaters.
"The Coast Guard is continuing to receive upwards of 1,000 calls per hour," US Coast Guard Lt. Mike Hart said on Monday. Police have rescued 3,400 people.
People have turned to the walkie-talkie app Zello to report their dire situations: an elderly couple trapped on a roof; a family caught in the maelstrom with three children, including one in the throes of a seizure and another with autism.
Search-and-rescue efforts unfolded at an inundated overpass in northeast Houston as residents walked through murky floodwater amid the rain. Many tried to help each other, and some guided seniors through the submerged street.
And the water won't stop rising anytime soon. Swollen rivers in east Texas aren't expected to crest until later this week, and federal officials are already predicting the deadly storm will drive 30,000 people into shelters and spur 450,000 people to seek some sort of disaster assistance.
-- President Donald Trump will head to Texas Tuesday to visit parts of the state battered by Hurricane Harvey over the weekend and to survey relief efforts.
"To the people of Texas and Louisiana, we are 100% with you," Trump said Monday, adding that he believes Congress will act quickly to provide disaster-relief funding.
-- Houston's George R. Brown Convention Center had 9,021 evacuees on Monday night, said Bob Mayer, Red Cross disaster program manager. Those who couldn't get a cot were given pillows and blankets to sleep on the floor, Red Cross spokeswoman Betsy Robertson said. Houston Mayor Sylvester Turner said city officials are looking for more shelter space.
-- Houston officials will not ask for immigration status or papers from anyone at any shelter, according to tweets in English and Spanish from the city's verified account.
-- Dallas is preparing to open a mega-shelter at its downtown convention center as the city has been asked to get ready for what could be tens of thousands of evacuees from Harvey. Authorities aim to open the Kay Bailey Hutchison Convention Center by Tuesday morning.
-- Houston so far has seen few cases of looting. Turner issued this stern warning: "No looting allowed. Don't take advantage, don't prey on people who are distressed and have to leave their homes because they have no choice."
-- The local district attorney's office will "seek prison or jail time in each and every forthcoming case where the defendant stands charged with theft (looting), burglary, robbery, or any similar crime committed during Hurricane Harvey," Montgomery County, Texas District Attorney Brett Ligon warned.
'None of us (is) giving up'
Thousands of calls for help have gone out across Houston.
Since midnight Sunday, more than 2,300 calls have poured in to the Houston Fire Department, including 400 calls for rescue Monday afternoon, Houston officials said Monday.
Houston police had rescued 1,000 people since Monday morning, bringing the total number rescued to more than 3,000 since the storm flooded the city, Turner told reporters Monday night.
State, local and military rescue units have plucked thousands of stranded residents from the water and deluged homes.
"None of us (is) going to give up," Houston Police Chief Art Acevedo said.
The Pentagon is identifying resources, including trucks, aircraft and troops, that can be dispatched for hurricane relief if the request comes, defense officials said. Texas Gov. Greg Abbott activated the entire Texas National Guard, roughly 12,000 Guardsmen, he said Monday.
In Harris County, authorities asked stranded people to hang sheets or towels from their homes so rescuers could spot them more easily.
The scope of how many people are trapped in flooded homes remains unclear.
Rep. Al Gree told CNN that he believes 10,000 people are still trapped in flooded homes in just one section of Houston he toured Monday. Rep. Sheila Jackson Lee said she believes the total number of trapped across Houston could be "tens of thousands."
Volunteers come to help
Citizens with boats were assisting authorities in search-and-rescue efforts. At a Monday news conference, FEMA Administrator Brock Long encouraged more citizens to volunteer, saying recovery efforts would require community involvement. The National Voluntary Organizations Active in Disaster website can direct people to religious and nongovernmental agencies that are helping people in at least 30 counties, he said.
But as water levels have risen, so has the desperation.
People started to panic, rushing rescue boats and even shooting at them if they didn't stop, one volunteer rescuer said.
Clyde Cain, of the Cajun Navy, a Louisiana-based rescue force that gained fame during Hurricane Katrina, said in one instance, a boat broke down, and while the crew sought shelter in a delivery truck, people tried to steal the inoperable boat.
"They're making it difficult for us to rescue them," he said. "You have people rushing the boat. Everyone wants to get in at the same time. They're panicking. Water is rising."
Jim McIngvale, who owns furniture stores in Houston and Richmond, also pitched in. He opened his doors to evacuees Sunday and gave 600 people a place to sleep.
"We have tons of mattresses in our warehouse, and we can provide them with a blanket," he told CNN. "We have a restaurant inside the stores, and we are feeding them for free."