But amid the rescues, the death toll continued to rise, hitting 18 by Tuesday night. Growing numbers of people have also been left homeless by the catastrophic storm.
A Houston police officer drowned when his car went into floodwaters from the Harvey storm, which has set a new record for extreme rainfall from a tropical system on the U.S. mainland.
The rains in Cedar Bayou, near Mont Belvieu, Texas, reached 51.88 inches as of 3:30 p.m. CDT. That's a record for both Texas and the continental United States but it doesn't quite pass the 52 inches from tropical cyclone Hiki in Kauai, Hawaii, in 1950 (before Hawaii became a state).
Later Tuesday afternoon, a mother was swept away by the waters as she and her daughter abandoned a vehicle stuck in a parking lot. The child survived and was found clinging to her mother's floating body by rescuers.
Houston Police Chief Art Acevedo, along with Mayor Sylvester Turner, confirmed the death of Sgt. Steve Perez, 61, at a Tuesday morning press conference.
On Sunday, Perez left his home at 4 a.m. in the heavy rain, trying to get to his work station. He called into the station saying he'd been driving for 2 1/2 hours to get to his duty station, but could not find a path, Acevedo said. He followed protocol and headed to a secondary station in Kingwood.
On Monday, Perez was not present at roll call and could not be reached, Acevedo added. There was an extensive search and at about 10 p.m. Monday, officials had a high probability that he was near the Hardy tollway and Beltway 8.
The dive team and members of the Cajun Navy were ready to search for him, but conditions were too treacherous and would put more officers at risk, Acevedo said as he cried.
A recovery mission was launched Tuesday morning, and a dive team found Perez's body at about 8 a.m. Acevedo said it appears he had driven from an underpass into the water and drowned.
Later Tuesday, Acevedo said the homes of more than 200 officers were flooded. The police department has also responded to nearly 2,000 calls since 5 p.m. Monday through Tuesday afternoon.
On Monday evening, Turner confirmed three deaths in Houston.
Four other storm-related deaths occurred in La Marque, Montgomery County, East Montgomery County and the coastal city of Rockport.
The Harris County Institute of Forensic Sciences updated its storm-related deaths Tuesday night to include an 89-year-old woman, Agnes Stanley, who was found floating in 4 feet of floodwater in a home. A 76-year-old woman was found floating in floodwater near a vehicle. Her name was not released.
A 45-year-old man, Travis Lynn Callihan, left his vehicle and fell into floodwaters. He was taken to a hospital, where he died Monday.
Family members and authorities have reported at least 18 deaths although the bodies of some victims apparently swept away in the floodwaters have not been found.
Crews on the ground, however, were preparing for the grim reality that fatalities may soar once the floodwaters recede.
As rainfall continued to pour from the Harvey storm, a major levee breached, and Texas officials told residents to "get out now."
Columbia Lakes residents in Brazoria County evacuated immediately, following orders from county officials.
Heavy rain from Harvey is expected to worsen the flooding in Texas and parts of Louisiana, leaving officials worried that the worst is yet to come.
The National Hurricane Center said the storm is expected to make a slow turn northeast and could dump another 10 to 20 inches of rain over the next two days.
Houston, the country's fourth largest city, has been inundated with flooding as result of Harvey, which made landfall late Friday as a Category 4 hurricane and lingered as a tropical storm over the weekend.
A mandatory curfew was issued Tuesday evening from 10 p.m. to 5 a.m. in an attempt to stop property crimes and ensure public safety.
The National Weather Service deemed the deadly flooding, which forced evacuations and wiped out homes, "epic and catastrophic."
The rainfall began to weaken, but residents still have to deal with 1 trillion gallons of water that has fallen since the storm began.
Texas Gov. Greg Abbott activated the entire Texas National Guard. The total number of guardsmen available to the state is roughly 12,000, and all of them will be used in support of recovery efforts in southeast Texas, according to Abbott.
In Houston, the largest shelter at the convention center has a capacity of 5,000 people, but as of Tuesday morning, it was housing more than 9,000 evacuees.
President Donald Trump left the White House Tuesday morning to tour the storm-damaged areas in Texas. He touched down in Corpus Christi at about 8:30 a.m. PST.
The Associated Press and ABC News contributed to this report.