Unfortunately, at this time visitors to the DR should by very cautious while traveling in the Southern part of the country.

Leaders of two rival bus owner groups are battling for the rights to certain territories and are using violence to achieve their goals. At this point the problems seem to be centered around the Santo Domingo area heading toward San Cristóbal. So using the countries public transportation North of Santo Domingo is probably still safe. Near Santo Domingo it might be best to use Taxis until this gets worked out.

You can view the articles written in Dominican Today at these links.
Dominican Republics owners strike again injure reporters
The country’s owners stage showdown over bus routes 7 injured
Dominican Republic owner mocks the Government from Congress
Dominican Republics owners continue standoff 2 injured