(CNN) -- Severe weather this weekend spawned tornadoes that devastated the country's heartland.
The greatest destruction was in the city of Joplin, Missouri, where at least 125 people were killed and a quarter of the city's homes and businesses were reportedly damaged.
As organizations and first responders provide emergency relief, food and shelter, many people across the country are looking for ways they can help.
Health professionals interested in volunteering are asked to sign up on the Missouri Department of Health and Senior Services Show-Me Response website.
The American Red Cross has opened shelters in Missouri and Minnesota. The shelter in Joplin is located at Missouri Southern State University, and the Red Cross is working to provide transportation to the shelter for those in need. The Red Cross is also distributing food, cleanup supplies and comfort kits, and sending health workers to provide immediate care.
Text "REDCROSS" to 90999 to make a $10 donation, or visit the website to donate, give blood or volunteer.
AmeriCares has sent disaster-relief personnel to Joplin, and it's working with Access Family Care Clinic to help victims. This expands AmeriCares' tornado relief operation, which has been assisting various Southern states as they recover from their own recent tornado outbreak.
Donations to AmeriCares can be made online or by phone at 1-800-486-HELP.
The disaster-response team with Convoy of Hope is heading to Joplin with a truckload of water, snacks and ready-to-eat meals. It is coordinating with local officials to determine what additional supplies should follow and at what locations they can provide essential supplies.
Those wanting to help can text the word "CONVOY" to 50555 to make a $10 donation. You can also donate online or by calling 1-417-823-8998.
The Heart of Missouri United Way has established the Tornado Relief Fund to help victims.
Text "JOPLIN" to 864833 to make a $10 donation, or call 1-573-443-4523.
Those interested in volunteering should list their availability and expertise on their Joplin Storm Recovery Volunteer Form.
For more opportunities to volunteer with United Way, call 1-800 427-4626.
Heart to Heart International has sent volunteer medical professionals and their mobile medical clinic to the devastated communities in Kansas and Missouri.
Heart to Heart also sends hygiene kits for people displaced by the storms, and their care kit assembly instructions can be found here.
You can donate or sign up to be a volunteer online or by phone at 1-913-764-5200.
Operation Blessing International has set up a base in Joplin to distribute relief supplies and coordinate volunteers to help local homeowners with repairs and reconstruction. It is accepting volunteers and donations to its Disaster Relief Fund.
The Salvation Army has mobilized four feeding kitchens in impacted areas of Joplin. It is also providing relief to other cities that were hit by the weekend tornadoes in Missouri, Minnesota, Kansas and Oklahoma.
The Salvation Army's disaster-relief efforts in Joplin can be supported by texting "JOPLIN" to 80888 to make a $10 donation. You can also donate through their website or by calling 1-800-SAL-ARMY.
Samaritan's Purse is providing assistance to survivors in Joplin. Its first volunteer team is on the ground, and it is asking for more volunteers to join their effort to remove trees and fallen debris and help make repairs on damaged homes.
ShelterBox has sent a disaster response team to Joplin, and it is working with local officials to determine where emergency shelters and supplies can aid those displaced by the disaster.
Donations to fund shelters and supplies can be made online and by calling 1-941-907-6036.
World Vision is now expanding its tornado relief to include the Joplin area. It has sent a team there to determine the most urgent needs.
Text"'TORNADO" to 20222 to give a $10 donation. You can also donate online or call 1-888-511-6443 to support World Vision's effort.