The governor of Texas on Monday activated the entire Texas National Guard in response to the flooding that has left a million people homeless after Hurricane Harvey.

The activation brings the number of Texas Guardsmen aiding in relief efforts to about 12,000, according to a news release from Gov. Greg Abbott’s office.

Military assets from across the country — aircraft, vehicles and emergency supplies — were sent to the Texas coast after Harvey made landfall as a Category 4 hurricane on Friday. Though downgraded to a tropical storm, continued rainfall is resulting in historic flooding in southeastern Texas.

National Guard units from Arizona, Florida, Louisiana, New Mexico, New York and Oklahoma are also helping those left in the storm’s wake.

The National Guard Bureau told Army Times that as of Monday morning, there were 16 helicopters aiding in recovery efforts, including 10 UH-60 Black Hawks, four UH-72 Lakotas and two CH-47 Chinooks.

The aircraft and personnel are conducting day and night wide-area search-and-rescue missions along the Texas coast from Corpus Christi to Houston.

The New York Air National Guard has provided one C-130, three HH-60s, and two C-17s. The Coast Guard and Air National Guard provided seven fixed-wing aircraft.

Upward of 400 Humvees and high-water vehicles have also been deployed, according to Sgt. 1st Class Mike Houk, a spokesman with the Guard Bureau.

Six helicopters from Guard units in Utah, Nebraska and North Carolina are now heading to Texas, he said.

The missions include search and rescue, bridging, water rescue, logistics movement, airfield openings and medical water purification, Houk said.

So far, no military forces in federal status have been deployed to help with hurricane relief efforts, said Army Lt. Col. Jamie Davis, a Defense Department spokesman. Active-duty units are headed to a staging area in case they are needed.

“U.S. Northern Command is poised to provide Department of Defense support to FEMA, state and local response efforts,” Davis said on Monday. “State and local agencies are in the lead for this response effort.”

National Guard responds to Texas flooding after Harvey

The Defense Department has sent Navy and Air Force search-and-rescue aircraft and personnel to Joint Reserve Base Fort Worth in Texas, officials said. Two search-and-rescue planners, nine rotary-wing aircraft, two fixed-wing aircraft, pararescue teams and command and control elements are all standing by.

Over the weekend, Navy Fleet Forces Command sent six SH 60 helicopters from Norfolk to Fort Worth, to be prepared to for search and rescue said command spokesman Lt. Cmdr. Brian Wierzbicki.

“They haven’t provided any support, because we have to wait for official tasking,” Wierzbicki said on Monday.

Four of the helicopters come from Helicopter Sea Combat Squadron Seven “Dusty Dogs” and the other two are from the Helicopter Sea Combat Squadron 28 “Dragon Whales,” said Wierzbicki, who couldn‘t say exactly how many Navy personnel have deployed to Texas.

They are the only Navy assets deployed to the region now, but said that could change in the near future, he said.

“We haven’t committed any other assets to go,”  Wierzbicki said. “We are in the planning stages and looking at available assets that we could push forward ― nothing is off the table, but we haven’t tasked anyone, but all that can change.”

The Navy has also begun preparations in case the amphibious assault ship Kearsarge and the dock landing ship Oak Hill are needed to participate in hurricane relief efforts, a Navy official said. The Kearsarge is based out of Norfolk and the Oak Hill is based at Virginia Beach. So far, Fleet Forces Command has not directed the ships to take any specific actions.

Team Rubicon, a group of veterans who assist with disaster relief, has dispatched three swift water rescue teams to Texas along with an advance team to assess the overall situation, said Duane DeVorak, a spokesman for the group. Those team members were traveling to Texas on Monday.

“We will not launch a coordinated presence in the area until we can ensure our volunteers will not also become victims,” deputy director of field operations Dennis Clancey said on Friday.

“We also want to ensure we do not drain strained emergency response resources. It could be a number of days, as soon as torrential rains subside. First step will be assessing the damage to determine where we can plug in to provide the greatest impact to the homeowners of greatest need, in the most vulnerable communities.”

U.S. Army North is standing by to help local, state and federal emergency responders in Texas, Lt. Gen. Jeffrey Buchanan said on Sunday.

“So far they have done a great job responding to the needs of the people, but the weather isn’t breaking so we will stay vigilant and increase our posture to assist as needed,” Buchanan said in a statement.

As of Monday morning, troops at Fort Hood, Texas, had not received orders to assist with hurricane relief efforts in Texas, a III Corps spokesman said.

The Associated Press contributed to this report.