The men ambushed the vehicle near Khuzdar, about 200km east of the Baluchi provincial capital, Quetta.
"Five soldiers and a civilian were killed in the attack," said military spokesman Major-General Shaukat Sultan in Islamabad.
One soldier and a civilian were wounded, he said.
Earlier police had said all the victims were army personnel.
Sultan said the soldiers were in civilian clothes and were going on leave.
"It is an act of terrorism. We have launched investigations," he said.
No group claimed responsibility for the attack.
In the past, police have blamed Baluchi nationalists for attacks on security forces and government installations.
Police blame Baluchi nationalists
for incessant attacks
The nationalists demand more control over the area's natural gas and mineral resources as well as political and economic rights.
They are also vehemently opposing government plans to build three military cantonments in the province, saying the government should allocate funds for development instead.
Trouble has been brewing in Baluchistan - Pakistan's biggest, but the least populated province - for the past several months.
There have been a spate of rocket attacks and bombings in various Baluchi cities and towns, specially targeting the natural gas supply pipelines.
"It is an act of terrorism. We have launched investigations"
Major-General Shaukat Sultan,
spokesman, Pakistan military
Our correspondent quoting tribal sources in Baluchistan province, said three time-bombs exploded on Saturday morning in Jwadar area, but there were no casualities.
The bombs went off in the fish port and in a store in the market area of the city.
In Jemn city, four people including police officers were killed during clashes between two rival parties, reported the correspondent.
Pakistan security forces launched a massive operation last week in Turbat area, about 380km south of Khuzdar, after an attack in which two soldiers were killed.
Thousands of paramilitary and regular troops have been deployed in the remote areas to protect the country's biggest natural gas fields and other government installations which are the main rebels targets.