Non-profit organization Hope for Haiti is providing relief to victims of the country's devastating earthquake in the face of major obstacles, its executive director, Elizabeth Davison, told Xinhua News Agency on Friday.

She said Hope for Haiti, whose mission is to improve Haitians' living conditions, had spent the past two days searching through the rubble for survivors and administrating first aid.

The 7.3-magnitude quake on Tuesday may have killed up to 45,000 people, according to UN preliminary estimates.

The organization's country director in Haiti, Mike Stewart, has taken a big red "tap-tap bus," a colorful local form of public transport, loaded with lifesaving supplies, materials for a makeshift trauma center and two doctors to Port-au-Prince from the southwestern Haitian seaport of Les Cayes half a day's drive away.

Davison, who is at the organization's Naples, Florida base in the United States, said "we wanted him (Stewart) to wait to make sure everything was safe but no way," adding Stewart didn't think twice about making the trip to Port-au-Prince.

Davison said the situation in Haiti had deteriorated from shock to desperation, according to information from Stewart.

"Just the horror -- the pain is setting in," Davison said. "There's just screaming. It's a terrible, terrible scene."

Stewart and his staff were currently manning three buildings and a hospital as part of their relief efforts, with one building used to hold about 500 dead bodies, Davison said.

"They are trying to find people alive to give them first aid," she said, adding Hope for Haiti's goal was to get more doctors and supplies into Port-au-Prince.

A major challenge has been logistics. The Haitian capital's port is severely damaged and aviation fuel is short, and aid agencies have been struggling to fly in vital supplies for days.

Davison said she had five doctors and four nurses packed with their backpacks at the Naples airport ready to go, but because of the lack of jet fuel in Haiti and in the neighboring Dominican Republic, they could not take off.

"We could get down there but we wouldn't have gas to get back," Davison said.

Instead, they are on standby. As soon as supply barges reached Port-au-Prince and the surrounding islands, the group would be on its way to the capital, hopefully by Saturday with an additional person, Davison said.

"I have got to get (Stewart) reinforcements," she said.

"We don't want people dying from secondary disease that can be prevented," Davison said, adding they also had a wound specialist ready to assist those in need.

As part of its relief effort, Hope for Haiti has cargo planes waiting in Naples -- all set to take teams, supplies and materials to Haiti.

Davison also expected the relief efforts to be a "steady stream of teams" for weeks to come, with Hope for Haiti medical personal across the United States "ready and willing to go."

Also ready for take-off in the next few days are two 757 Boeing planes in Miami, Florida, which Davison said had enough fuel to go back and forth -- one was donated by a private donor and the other by General Electric, Davison said.

The two planes will be packed to the brim with much needed supplies, which Davison said would include nails and wood for the "mini dorm" that Stewart would build for the staff's sleeping quarters.

"We've been making a difference in Haiti for 20 years, but now we're going to be making even a bigger difference," she said.