The Salvation Army has set up 10 mobile kitchens to provide hot meals to survivors in hard-hit areas like Tuscaloosa, Guntersville and Lauderdale in Alabama and Montpellier and Oxford, Mississippi.
Another 22 mobile kitchens are on standby.
Samaritan's Purse has dispatched experts and two disaster relief units, tractor trailers stocked with emergency supplies and tools, to assess the needs in Tuscaloosa, Birmingham and Cullman, Alabama.
Visit Samaritan's Purse online to volunteer or make a donation to help the storm victims.
The American Red Cross has more than 30 emergency response vehicles en route to provide food and to hand out clean-up and comfort kits.
The organization is prepared to distribute up to 25,000 ready-to-eat meals to affected communities.
The Red Cross also operates a National Shelter System Google map where people can find information about shelters in their area.
Text "REDCROSS" to 90999 to make a $10 donation or visit the website to donate, give blood or volunteer.
Feeding America mobilized a quick response team to get food and water into the hardest hit areas and is working with Alabama-based food banks to assess their immediate needs.
The organization's disaster relief food items, including ready-to-eat meals and bottled water, are currently en route to Alabama for victims and relief workers.
Go to the website to make a donation to help food banks provide meals to communities affected by the tornadoes.
LifeSouth Community Blood Centers is declaring "there is an emergency blood shortage" in Alabama, according to J.B. Bowles, vice president of operations.
The organization typically carries 3½ days worth of blood, but the storm almost completely depleted their stores, Bowles says. They are nearly out of O-negative (universal donor) and are having to ship emergency supplies from out of state.
Visit the website for information on how to donate blood.
The Billy Graham Rapid Response Team of crisis-trained chaplains has staff on the ground in Birmingham assessing the damage.
The group, which deployed in coordination with Samaritan's Purse, will address the emotional and spiritual needs of tornado survivors in and around Birmingham and Tuscaloosa.
Those wanting to help the response team in Alabama may text "RRT" to 85944 to make a $10 donation.
Hands On Birmingham is preparing to organize volunteer groups to help in affected areas once the search and recovery efforts have concluded.
Visit the website for ways to volunteer in Jefferson and Tuscaloosa.
A Facebook match-up page has popped up to reunite owners with tornado-strewn items, such as photos and documents.
Visit the Facebook page to search for lost items or post pictures of things found.