Abbott held a briefing at noon Wednesday about what the state will do in the wake of the storm that's already predicted to leave behind devastation to life and property.
He said those living in certain areas of southeast Texas who are closest to the point where Hurricane Laura will come across shorelines only have about five hours to evacuate, Abbott said.
He said any rescues will begin Thursday.
"It's important for people to know that from about 7 p.m. [Wednesday] until about 9 a.m. [Thursday] morning, it will be a little bit of a lockdown time period for the ability of rescuers and aiders to get in and provide support for anybody in the local regions," he said. "We urge everybody who may be in harm's way to take these few last hours to get out of harm's way. It may only be a day or two."
So far, the state has already sent out 400 buses, 38 planes, 82 boats, 202 high profile vehicles and 60 ambulances to help with any rescue efforts, according to Abbott.
Abbott said three more Texas counties have been added to the state's disaster declaration, which includes Camp, Ellis and Tarrant counties. He said Ellis and Tarrant are serving as sheltering locations.
"We remain flexible with regards to expanding the counties that could be added," said Abbott. Ahead of the storm, President Trump approved Abbott's state of disaster declaration for the state, which orders federal assistance to supplement state and local response efforts.
INTERACTIVE MAP: Track updates to Hurricane Laura's path as they come out
The president's action authorized the Department of Homeland Security and Federal Emergency Management Agency (FEMA) to coordinate all disaster relief efforts.
WATCH: Gov. Abbott announces disaster declaration ahead of Laura's landfall
These are the Texas counties under the disaster declaration: Aransas, Bexar, Brazoria, Calhoun, Cameron, Camp, Chambers, Ellis, Galveston, Hardin, Harris, Jackson, Jasper, Jefferson, Kenedy, Kleberg, Liberty, Matagorda, Newton, Nueces, Orange, Refugio, San Patricio, Tarrant, Victoria and Willacy.