Monday's tornado outside Oklahoma City — upgraded on Tuesday to a category EF-5, the strongest type of tornado — wrought catastrophic damage across the area, shredding fields, demolishing buildings, and leveling homes. With hundreds injured or displaced, dozens reportedly dead, and damages estimated to reach as high as $2 billion, there is plenty of clean-up and rebuilding to do.

At the federal level, President Obama has declared a state of emergency and pledged to offer all assistance within his power. He signed a disaster declaration that will allow the Federal Emergency Management Agency to provide temporary housing and to offer loans and grants to businesses and homeowners. The declaration also provides Oklahoma with direct material assistance in the form of food, bottled water, and other supplies.

"As a nation, our full focus right now is on the urgent work of rescue, and the hard work of recovery and rebuilding that lies ahead," he said Tuesday. "The people of Moore should know that their country will remain on the ground, there for them, beside them, as long as it takes."

FEMA has sent an Incident Management Assistance Team to Oklahoma City to coordinate Washington's efforts with local disaster response agencies. FEMA has also deployed search-and-rescue teams with additional telecommunications and logistics support equipment, and placed agents in Texas on call in case they're needed.

FEMA chief Craig Fugate has already traveled to Oklahoma, and Homeland Security Secretary Janet Napolitano will head there on Wednesday.

In Oklahoma, Gov. Mary Fallin (R) had already declared a state of emergency on Sunday for 16 counties that were hit by tornadoes and severe weather over the weekend, and asked the federal government for disaster assistance. The state has also set up a disaster response website specifically for these crises, called OKStrong, to provide information to those affected by the storms, and to those who wish to help.

Dozens of state and local fire, police, and disaster response crews, including Oklahoma's Department of Emergency Management and the Oklahoma Highway Patrol, are on site to clean debris and pick through the rubble for survivors. According to Gary Bird, fire chief in Moore, Okla., which bore the brunt of Monday's tornado, some 200 people worked through the night to find survivors.

Nearly 250 members of the Oklahoma National Guard have been called up to aid in search-and-rescue operations, and the state has requested additional disaster response personnel from Texas to help identify victims and determine causes of death. In addition, hundreds of volunteers and crisis teams from across the nation, including firefighters from California and relief workers from New York, have headed to Oklahoma to offer whatever help they can.

Dozens of non-profits have also stepped in, soliciting donations and sending their own volunteers and supplies. The Red Cross has sent 30 emergency response vehicles to the area and has set up shelters for those displaced by the storm. The organization is also asking for cash and blood donations.

On Tuesday, Oklahoma City Thunder All-Star forward Kevin Durant donated $1 million to the Red Cross through his charity. His team and the NBA followed suit later that day. Chesapeake Energy Corporation, which owns the naming rights to the Thunder's arena, has also chipped in $1 million.