George Clooney
George Clooney (Reuters)Reuters

George Clooney and Amal Alamuddin celebrated their engagement at Cafe Habana in Malibu, Calif., on Sunday, May 11.

The couple was seen marking the occasion with close friends including U2 frontman Bono, the restaurant's owner Rande Gerber and his supermodel wife, Cindy Crawford. Clooney and Gerber are long time friends.

The newly engaged pair kept the affair low-key and celebrated at the back of the restaurant under a covered patio. Love was in the air and there was a lot of hugging and kissing. Throughout the party, Alamuddin flaunted her diamond ring and the group toasted with shots of tequila.

The restaurant was crowded due to mother's day celebration and fans were evidently delighted to catch an unexpected sight of the couple.

"People got a show they didn't expect and other [restaurant patrons] said it was the best Mother's Day ever," a source present at the hotel told E! News.

"Bono actually got up and sang, as did Crawford, who belted out a tune with her daughter. Clooney looked very relaxed and was constantly smiling and laughing, adding that he and Alamuddin definitely appeared happy and in love," the source further said.

Clooney proposed to Alamuddin over a meal, which he apparently cooked himself.

"George cooked a meal himself for Amal at home on April 22, then he surprised her by getting down on bended knee and presenting her with the ring. He was so happy she accepted, he was calling friends with the news later that night,"  Page Six quoted a source.

Alamuddin is a British lawyer by profession. She and Clooney were first spotted together in October 2013. They were also seen attending a private white house screening of one of the Clooney's movies. Buzz is it that the couple could walk the aisle by the end of this summer.