Jennifer Lopez thrilled her children by letting 500 balloons fly into the air.

The singer-and-actress has twins Max and Emme with her estranged husband Marc Anthony. They turned four in February and Jennifer celebrated with a lavish party.

As part of the bash she organised for 500 helium-filled balloons to decorate the grounds of her San Fernando Valley home. The children were delighted especially when Jennifer let them loose.

"It took several trucks just to deliver them, and Jennifer's backyard brimmed with balloons. But when the party was over, rather than have her staff pop them all, she told them to cut the strings and let em fly," a source told National Enquirer.

The tots and their friends were heard shrieking with excitement. However, some of Jennifer's neighbours were said to be concerned about the impact the balloons would have on the environment.

Jennifer split from Marc last year and they are currently in the process of divorcing. She is now dating her backing dancer Casper Smart, but has refuted reports they are planning to wed.