Story highlights Hurricane Sandy wreaked havoc on millions of people as it made landfall Monday

Relief groups are working to take care of those affected

There are ways you can help from wherever you are

If you choose to donate, make sure the charity is legitimate

Though no longer a hurricane, Sandy still brings the threat of flooding, snow and massive power outages to millions.

The deadly storm wreaked havoc as it made landfall Monday night, and many evacuees remain in temporary shelters. Even residents riding out the storm at home face significant damage and a tough cleanup in the days ahead.

Relief groups are already working to make sure everyone affected by the storm is cared for, and you can help.

Donate blood -- The Red Cross had to cancel about 300 blood drives because of the storm and supplies are running low. Visit -- The Red Cross had to cancel about 300 blood drives because of the storm and supplies are running low. Visit RedCrossBlood.org or call 1-800-RED-CROSS to schedule a donation appointment in your area. The New York Blood Center is also collecting blood donations in the New York/New Jersey area.

Give food and shelter -- The -- The Red Cross and the Salvation Army are providing emergency shelter and meals for evacuees.

Help children in need -- -- Save the Children and World Vision are paying special attention to the needs of children affected by the storm.

Join in the cleanup -- -- Team Rubicon has dispatched veteran field teams to start working right away, and Samaritan's Purse is looking for volunteers to help rebuild after the storm passes.

Help outside the U.S. -- Hurricane Sandy took a deadly toll on the Caribbean before it hit the United States. -- Hurricane Sandy took a deadly toll on the Caribbean before it hit the United States. Operation USA and the International Medical Corps are helping people affected by Sandy in Haiti and Cuba. Operation USA is also providing aid to the East Coast.

Say informed - For more ways to help, visit - For more ways to help, visit Impact Your World . If you are in the Northeast and know of a need where you live, tweet @CNNImpact