The hurricane is expected to cause severe damage.
Sounding alert, Governor Greg Abbott has warned citizens of record flooding.
US President Donald Trump has signed a disaster proclamation for the state and said he is monitoring the situation closely.
"At the request of the Governor of Texas, I have signed the Disaster Proclamation, which unleashes the full force of government help!" Trump's tweet read.
The US president has also urged Texans to live safely.
"We will remain fully engaged w/ open lines of communication as #HurricaneHarvey makes landfall. America is w/ you! @GovAbbott @FEMA @DHSgov," another tweet read.
Trump is expected to visit Texas early next week.
The category four storm has already uprooted several trees in Corpus Christi.
Thousands have been evacuated so far.
Meanwhile, a city manager said that few people were trapped inside an old-age facility after the roof of the building collapsed.
Rescue team members were quoted as saying that they were unable to gain access.
The hurricane is deemed the worst to hit Texas in 12 years, with an expected rainfall of over 40 inches in the next couple of days.
At least 1,000 National Guardsmen have been deployed by the state to tackle the situation.
Hurricane Harvey has also hampered operations in Gulf of Mexico oil production and air travel.
The National Hurricane Center has warned that the storm may be bring life-threatening floods in and around Houston.
Forecasters said that the path of the hurricane is uncertain as of now, but expect it to be near the middle of Texas coast.
How to deem the category of a storm:
There are five categories in the Saffir-Simpson Hurricane Wind scale.
Category One: Wind speed upto 153 km/hr. Slight damage and power cuts.
Category Two: Wind speed 154-177 km/hr. Significant damage.
Category Three: Wind speed 178-208 km/hr. Building suffering major damage.
Category Four: Wind Speed 209-251 km/hr. Trees blown over. Building suffering major damage.
Category Five: Wind Speed 252+ km/hr. Trees blown over. Building suffering major damage. Major roads cut off.
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