Some of the deportees have said they were threatened to leave. Dominican police say people wanted to leave because they feared being victims of mob violence.
The exodus began Saturday, with 244 people, after an elderly Dominican couple was slain during an apparent burglary near the town of Neiba, and a mob of Dominicans retaliated by killing a Haitian man. On Monday, 113 more people followed, Metzner said.
Dominican officials have since tightened restrictions on the border, ensuring that Haitians and others trying to cross have authorization. Ordinarily, the frontier is wide open and many people freely move between the two countries.
In and outside Neiba, the few Haitians visible in the streets say they aren't eager to be in public for long.
"We're forced to be afraid, because we're not in our country," farmer Aubin Pierre, 25, said as he walked along a highway.
A Dominican soldier played down the significance of the violence, saying the area outside Neiba is dangerous.
"You can't go there," Sgt. Enrique Canario said at one of several checkpoints between Neiba and the border. "If you go, you will be killed."
The removals come amid a politically delicate time for the two nations, which share the Caribbean island of Hispaniola. Two months ago, a Dominican court ruled that citizenship should be stripped from residents born to migrants who were living in the country illegally, and many of those affected are of Haitian descent.
Advocates say 200,000 people could lose their citizenship and documents they need to work or attend school. The Dominican government said in a preliminary report that only about 24,000 people would be affected.
The Caribbean Community condemned the court decision during a meeting Tuesday. The trade bloc also put off voting on the Dominican Republic's application to become a member.