Residents in Galveston and Port Arthur, Texas, were ordered to evacuate as Hurricane Laura strengthened in the Gulf of Mexico Tuesday night en route to its expected landfall late Wednesday.
The mandatory evacuation order was signed Tuesday morning as the storm headed toward Houston. The mandatory evacuations will be ongoing through early Wednesday, officials said, citing the "uncertainty of the path and the heightened intensity of this storm."
City services were suspended at noon local time. The state will be providing buses throughout the area for those residents who have signed up for transportation assistance.
"With the uncertainties of this storm and its increasing strength, we need to take all necessary precautions to protect our residents," Galveston Mayor Craig Brown said early Tuesday. "It's imperative that you make plans this morning to secure your homes and move you and your family to safety off the island."
He urged residents to secure loose items and leave the island, adding that it was "urgent that residents heed this mandatory evacuation and leave with all family members and pets."
Officials in Orange County, Texas, also issued a mandatory evacuation order for all residents. The county noted that first responders wouldn't be able to travel once winds reach 35 mph.
Residents in Port Arthur, Texas, located about 110 miles northeast of Galveston, were also under mandatory evacuation orders. The mandate was a "direct result of the imminent dangers" from Laura and Tropical Storm Marco, a separate storm system in the Gulf of Mexico that's forecast to make landfall on the Southeast Texas coastline mid-day as a tropical depression. It's expected to produce heavy rainfall and wind gusts up to 30 miles per hour.
City officials in Houston and Harris County urged residents to stay off the roads so people evacuating have access to the freeways. Local officials urged all residents in the storm's path to fill up their gas tanks and generators now.
"People are going to be evacuated, either from Port Arthur, from Chambers to Galveston County, to the extent that is called for, to allow them to kind of get through on, going into Wednesday," Houston Mayor Sylvester Turner said in a statement.
He added, "Harvey was a rainy event. This one, for example, would be more of a windy day. We are certainly more prepared than we were three years ago. We learned a lot from Hurricane Harvey but you cannot compare Harvey, with what we are dealing in this particular case."
Hurricane Laura has kept people along the Gulf Coast guessing for days as the projected track continues to change. Turner said he woke up Tuesday to find Laura's track had shifted slightly west and closer to Houston, the country's fourth-largest city with a population of about 7 million.
In an interview with ABC News Tuesday, the mayor urged people not to panic. City officials said they don't expect Laura to be another Hurricane Harvey or Tropical Storm Imelda, which both led to catastrophic flooding. They do, however, expect this storm to be a fast-moving wind event, which could bring a storm surge, structural damage and power outages.
Compounding the situation, of course, is the pandemic, which is why Turner told residents to stock up on necessary food, supplies and PPE. He said he anticipates that COVID-19 testing will be suspended until after the storm and the city won't be opening mass shelters as it has in years past.
Galveston County also issued voluntary evacuation orders for residents on the Bolivar Peninsula, including the unincorporated areas of Port Bolivar, Crystal Beach, High Island and Gilchrist, where inundation models currently show a possible 3 feet to 6 feet of flooding on the Bolivar Peninsula.
The voluntary evacuation could become a mandatory evacuation depending on further weather updates, county officials said.
The Port of Galveston closed Tuesday afternoon until further notice. The state is also suspending ferry operations from the Bolivar Peninsula starting at 11:30 p.m. local time Tuesday.
Voluntary evacuation orders were issued Tuesday evening for several other low-lying areas and coastal communities in southeastern Texas.
ABC's Houston station KTRK shared powerful images, showing intense gridlock as people evacuated the Galveston area.
Over 130 flights scheduled for Wednesday have been canceled at George Bush Intercontinental Airport ahead of the hurricane, according to FlightAware. All major U.S. airlines -- including United, Southwest, Delta, American and JetBlue -- have issued weather waivers to allow travelers to adjust their flights without fees.
Laura is currently strengthening as it moves through warm water in the central Gulf of Mexico, with sustained winds up to 85 mph. Landfall is expected to occur on late Wednesday night or early Thursday morning with possible storm surge of up to 13 feet in parts of eastern Texas and western Louisiana.
Tuesday evening, Louisiana Gov. John Bel Edwards also advised coastal residents to prepare for storm surge, warning that parts of the state could start seeing an impact starting Wednesday morning.
"It's going to be a large, powerful storm," Edwards said.
ABC News' Welington F. Gomez-Muñoz, Rachel Katz, Marcus Moore, Alyssa Pone and Gina Sunseri contributed to this report.