The Dawn newspaper, quoting the officials and sources, said the bus traveling from the provincial capital of Quetta to neighboring Punjab province was stopped on a highway Thursday night near Bolan district by a group of armed men, who then kidnapped the passengers.
A local official was quoted as saying the journalist with a Quetta newspaper and two others were gunned down when they tried to escape.
"The armed men took the [other] three other passengers with them," the official told the newspaper.
The report said a trucker driving on the highway was injured in the shootings.
Authorities recovered the bodies of the three and took the injured truck driver to a local hospital, the report said.
There was no immediate claim of responsibility for the shootings.