ARLINGTON, Va. -- The National Guard response to Hurricane Harvey will be a long term, sustained effort, said a senior National Guard official, adding that up 30,000 Guard members stand ready to assist with those efforts if needed.

"We are leaning as far forward as we possibly can to ensure that military assets are postured to support the needs of Texas and potentially Louisiana," said Air Force Maj. Gen. James C. Witham, the director of domestic operations at the National Guard Bureau.

More than 4,300 Guard members are on duty in Texas as of Wednesday morning, primarily assisting local authorities with search and rescue operations. Texas Gov. Greg Abbott has called up the entire Texas National Guard, numbering around 12,000 Soldiers and Airmen, who may be brought on duty gradually over the next few days as needed, said Witham.

As of Tuesday afternoon, Guard members have taken part in more than 3,500 rescues of those affected by the storm, mostly in the Houston area.

"Most [rescues] have been by some type of boat, but these also include almost 300 hoist rescues [by helicopter], which are very technically difficult," said Witham, adding that weather conditions initially prevented helicopter crews from flying.

Some 30 helicopters are currently in use by Guard aircrews, said Witham, and additional helicopter assets have been requested through the Emergency Management Assistance Compact, which allows Guard elements from one state to assist in other states in emergency situations.

"[Aircrews] are supporting not only airborne search and rescue efforts with hoist capacity, but also supporting [medical evacuation] capacity as required," said Witham.

Currently, Guard elements from 10 states are supporting Harvey response operations, with some coming from as far away as Alaska.

"As you talk response and recovery, our response is very sustained," said Witham, adding that the storm's unprecedented amount of rainfall has made for a different sort of hurricane response.

"When the Guard responds to hurricane-type events, normally we talk about that first 72 to 96 hours for the lifesaving and life-sustainment that takes place. Then, we're into the recovery effort," he said. "Due to the nature of this storm as it spun across southeast Texas for days and dumped historic levels of rainfall, our response has been very different than what we've looked at before."

Meanwhile in Louisiana, the storm made its second landfall early Wednesday as it continues to move eastward. Soldiers and Airmen with the Louisiana National Guard pre-positioned equipment and supplies in advance of the storm, said Witham, adding that approximately 400 Soldiers and Airmen are currently on duty.

But Louisiana Guard members were busy in other ways before the storm made landfall.

On Monday, Soldiers with the Louisiana Army National Guard's 3rd Battalion, 156th Infantry Regiment rescued more than 100 people in the Lake Charles, La., area, roughly 35 miles east of Texas. Unit members assisted local first responders with the rescues, and are anticipating additional rescue efforts in the coming days.

"In the next 24 hours, I think they predicted anywhere from 5-10 inches of rain," said Army Maj. Aaron Duplechin, commander of the unit. "So it just kind of depends on when those bands hit and where."

Witham said the response in Louisiana was no different from response efforts in Texas and Soldiers and Airmen continue to respond as needed.

"We are very proud of the Texas Guard [members] who have responded at this point," he said. "The Soldiers and Airmen have been working around the clock…to alleviate the pain and suffering that has been experienced by the citizens in Houston and southeast Texas."