From People: “Brad Pitt sure knows how to throw a party – for a good cause.

The 12 Years a Slave producer, fiancée Angelina Jolie and several of their friends – like A-listers Sandra Bullock and Sofia Vergara – were in New Orleans Saturday night for the second annual Make It Right gala.

Chris Rock hosted the star-studded soiree, while Bruno Mars and Kings of Leon were the musical guests. Comedian Jim Gaffigan cracked up the audience, at one point “describing his remarkable resemblance to Brad Pitt,” a guest tells PEOPLE.

When it came time for fundraising, the nonprofit’s founder and event chairman Pitt, along with pal Bullock, took to the stage to run the live auction.

“The highlight of the night was Brad and Sandy Bullock encouraging the crowd to buy a Make It Right home, alternatively funny and moving,” the guest says.

“The two of them were great together,” says the guest, noting how they encouraged guests to purchase homes outright to give to residents in need.

“Sandra was hilarious. They were bantering back and forth. It was like they were on The Price Is Right, taking bids.”

Every guest who pledged $10,000 was eligible to win a BMW i3, and “Brad and Sandra pulled the winner’s name out of a hat at the end of the night,” the guest says.

By the gala’s end, the pair raised more than $4 million – with many of the event’s celebrity guests buying homes for those in need.

Pitt founded the organization, which builds sustainable homes and buildings for communities in need, in 2007, following the devastation left by Hurricane Katrina. Besides New Orleans, Make It Right also has projects in Montana; Newark, New Jersey; and Kansas City, Missouri.

“You can’t believe the change in the Lower Ninth Ward,” says a guest who toured the Katrina-ravaged neighborhood in New Orleans. “There are 100 of these bright homes, families are back, kids are out playing. It’s so great.”

To donate, visit makeitright.org.”

View photos online here at People.