Dozens of gravely injured Haitians sought refuge and medical attention in neighboring Dominican Republic on Wednesday, a AFP journalist at the scene said.
Buses from earthquake-struck Port-au-Prince arrived to the General Meleciano Hospital, 280 kilometers (173 miles) west of Santo Domingo, carrying the injured.
President Leonel Fernandez ordered border hospitals to open their doors.
But Dominican authorities also stepped up immigration controls fearing an influx of illegal migrants and convicts who had escaped from the wreckage of a Port-au-Prince prison.
Victims were seeking treatment for a range of serious injuries from badly-damaged limbs to skull fractures.
The most serious cases were transferred to larger hospitals, Dominican authorities said.
Earlier on Wednesday members of the UN peacekeeping force in Haiti were transferred to the Dominican capital of Santo Domingo for treatment.
Haiti has long had troubled relations with its eastern neighbor, which has frequently been bombarded with refugees fleeing Haiti's political and natural disasters.
In the 1930s, Dominican dictator Rafael Trujilo ordered the slaughter of tens of thousands of Haitians in an assault on the border.
Mistrust between citizens of the two countries remains strong, but it appeared to be put aside Wednesday, as Dominicans offered help to their neighbors from the western third of Hispaniola.
Other Dominican hospitals near the border also received injured Haitians, including those in Barahona province.
In Jimani, a logistics center was also set up for aid groups to use. Trucks carrying water and food left from the camp along with mobile kitchens, the first batch of a mission to supply around 10,000 meals a day.
Doses of tetanus shots were also being transported, local media reported.
The Dominican military and police were reinforcing rescue teams looking for survivors on the other side of the border.