Mourning arrived in the devastated capital Friday morning on a plane with Project Medishare, a Miami-based nonprofit agency that has worked since 1995 to provide health care in Haiti.
"I've been working nonstop assisting all of the doctors from all over the world for the past seven hours," Mourning told The Associated Press from Port-au-Prince, his cell phone repeatedly breaking up. "We've got a lot of patients here, babies, mothers who need a lot of help. We're running out of supplies, water. People are homeless, people are hungry, it's such an extreme need for assistance on all different bases."
Mourning was at a tent city at the United Nations compound, where he plans to remain through Saturday. He and Wade are calling their venture the "Athletes Relief Fund for Haiti."
"It's been a humbling experience. I walk through here with extreme concern and a heavy heart because you've got all these people around you who are suffering," Mourning said. "Babies suffering, mothers and fathers suffering, everybody suffering. It's extreme devastation here.
"There's people screaming. I see bones protruding out of people's bodies. It's hard to see people suffer like this."
Speaking from Houston, where the Heat were playing the Rockets on Friday night, Wade said he thought the immediate effort to enlist other NBA players to help was "going pretty good."
Numerous other athletes, leagues and organizations have also offered quick responses to the Haitian crisis since the earthquake struck Tuesday, causing the deaths of up to 50,000 people.
"I know so many players want to do something but don't know exactly what, so we're trying to reach out to everyone," Wade said. "The main thing we ask is for people to give, whether it's a full-game salary, a half-game salary, whatever's in your heart to give. We want to make sure all athletes get together, because there's strength in numbers."
The Heat have announced plans to send money and supplies, asking fans to give in exchange for ticket vouchers to February games. Mourning is a vice president within the organization.
Mourning said if his foundation, Alonzo Mourning Charities, raises $1 million for Project Medishare and Haitian relief, a private donor has agreed to match that money.
"The pictures that you see at home don't do this justice," said Mourning, who decided Thursday to make the trip after meeting with Miami doctors who were also headed to Haiti.
Mourning said the plane he was on had been loaded with cardboard boxes filled with supplies. One of his jobs at the clinic was to cut up the empty boxes and use them as splints for people with broken bones because "nothing else is available."
Wade and Mourning had previously held conversations about trying to help the impoverished Haitian community, which has a large base in South Florida. The NBA players have teamed up for charitable causes in the past, most notably the annual Zo's Summer Groove in Miami, which has raised more than $6 million for children's programs.
"The Haitian community has deep roots in Miami, a city which I have personally claimed as my own home for 15 years," Mourning said in an earlier statement to The AP. "I feel a profound sense of sadness for my many affected friends and neighbors."