Katy Perry, Pitbull and Kristen Bell are among the stars who have urged fans to dig deep for the victims of the Oklahoma tornado tragedy. A giant tornado swept through the suburbs of Oklahoma City on Monday (20May13), leaving more than 90 dead and destroying schools and neighbourhoods in a nearby city called Moore, the hardest hit. Several stars took to Twitter.com and called on their U.S. followers to make donations to the American Red Cross, which has opened several shelters and is helping to reconnect loved ones separated in the disaster. Perry tweeted, "Sending out prayers for the people of Oklahoma tonight. Let's help, just text REDCROSS to 90999 to donate 10 dollars to those in need," while Pitbull also told fans he had given $10 ($6.40) to the cause. Screen stars Ricky Gervais, Ginnifer Goodwin and Kat Dennings also encouraged their Twitter followers to make donations, while Forgetting Sarah Marshall star Bell shared a link to the Oklahoma Tornado Victims Fund, which will benefit those who will now have to rebuild their communities.