Celebrities led by Sandra Bullock on Wednesday poured millions of dollars into relief efforts after monster storm Harvey ravaged Houston.
Bullock, who maintains homes in nearby Austin and New Orleans, donated $1 million through the American Red Cross, the organization said.
"I'm just grateful I can do it," Bullock, the star of Hollywood hits such as "Gravity" and "The Blind Side," said in a statement.
Socialite Khloe Kardashian said that her celebrity clan was donating $500,000 to the Red Cross and the Salvation Army.
She was responding to a challenge set by the comedian Kevin Hart, who on Tuesday said he was donating $25,000 and named celebrities whom he urged to follow suit.
In response, pop star Jennifer Lopez and her boyfriend, baseball legend Alex Rodriguez, in a joint Instagram post said that they were each donating $25,000.
"Seeing these pictures of children and all the footage, it's just devastating, and we just want to do our part to help," Lopez said.
Rapper Nicki Minaj, hip-producer DJ Khaled and actor and wrestler The Rock were among other celebrities to respond to Hart's challenge and donate $25,000.
The Rock urged Houston to stay strong and thanked Hart but, in perhaps an indirect criticism of the comedian's name-shaming, said he was "not going to call out my celebrity friends -- you guys already know what to do" and urged small donors to come forward with "a buck or two."
Chris Brown, the R&B singer infamous for his legal troubles, told Hart he was donating $100,000 but without explanation said his money "will go to the people" as he was skeptical of the Red Cross.
The country singer Chris Young also said he was donating $100,000 and urged fans to join him.
One of the most successful fund-raising efforts came from football player J.J. Watt, a local transplant who plays for the Houston Texans.
After his online appeal quickly met his goal of raising $500,000 in donations, he repeatedly upped the challenge. By Wednesday he had raised $6 million and was seeking $10 million.
Beyonce, one of the top stars to emerge from Houston, and hip-hop mega-star Drake, who has a home in Houston, have both said they are working on generous relief plans but have not yet revealed the details.
Amal Clooney has given birth to twins - a girl named Ella and a boy named Alexander.
They were born in London on Tuesday morning, the publicist of her actor husband George Clooney said.
"Ella, Alexander and Amal are all healthy, happy and doing fine," Stan Rosenfield said before joking: "George is sedated and should recover in a few days."
George, 56, married the lawyer, 39, in September 2014 in Venice.
Amal Clooney's parents said they were delighted to welcome their grandchildren.
"They are in great health, all is perfect," Amal's father Ramzi Alamuddin, who lives in Beirut, told AFP news agency.
"I am very happy for them, they will be great parents."
Amal's mother Baria, who is in hospital with her daughter, said: "We are over the moon. It was a beautiful delivery. The babies are beautiful and are doing well."
Other celebrities have congratulated the couple.
Actress Nicole Kidman, speaking at the Glamour Women Of The Year awards in London, said: "Any time a baby is born, I'm like: 'Ahhh'. So two babies it's double 'ahhh'. They have the most joyful journey ahead."
Mia Farrow also added her best wishes, tweeting: "Wishing Ella and Alexander Clooney a warm welcome and every blessing - and congratulations to Amal and George!"
Comedian and TV host Ellen DeGeneres tweeted: her best wishes with a reference to George Clooney's Oceans Eleven film franchise: "Welcome to the world, Ella and Alexander Clooney. Congratulations, George and Amal, or as I'm now calling you, Ocean's Four."
Social media reaction has included comments about how "normal" the twins' names are.
One Twitter user wrote: "Classy people give their kids classy names. Ella and Alexander."
And another tweeted: "What, George and Amal Clooney gave their new twins nice normal names? Ella and Alexander. Isn't that a violation of celebrity rules?"
The couple's friend, actor Matt Damon, confirmed that Amal was pregnant with twins back in February.
He was speaking after the news of the pregnancy was reported by CBS's The Talk host Julie Chen.
Explaining how Clooney revealed the news, Damon said: "I was working with him last fall and he pulled me aside on set and I almost started crying.
"I was so happy for him. And I was like, 'How far along is she?' And he goes, 'Eight weeks.'
"I said, 'Are you out of your mind? Don't tell anybody else! Don't you know the 12-week rule?' Of course he doesn't. I was like: 'Just shut up, man.”