Demi Lovato Volunteers in Houston with Kevin Hart & Chris Paul

Demi Lovato's on a mission to help with Hurricane Harvey relief efforts, and while volunteering at the Houston Food Bank she ran into Kevin Hart and NBA superstar Chris Paul.

We're told Demi donated 50,000 bottles of water to the food bank after hearing about price-gouging in the area -- and she set up a fundraising initiative with the food bank after donating $50k of her own dough.

Chris and Kevin were helping unload trucks and serve food. We're told the trio randomly bumped into each other and snapped a quick pic.