"The four policemen were on two motorcycles on their routine patrol along the railway track when unknown armed men opened fire at them," Deputy Inspector General (Operations) Qazi Wahid said.
"The slain police officials were deputed there following the request of railway officials," he added.
All the four policemen were killed on the spot, while the assailants managed to escape on motorbikes.
Security has become a major issue in the Baluchistan province in recent times with most attacks on security forces, government officials, politicians and government installations blamed on separatists or militants or to sectarian violence.
Security across the provincial capital was beefed up following the incident.
The deceased were identified as Constable Razar Mohammad, Constable Hafeez-ur-Rehman, Constable Sarfaraz and Constable Abdul Kareem.
The funeral prayers of policemen were offered at Police line Quetta and bodies were handed over to their relatives for burial.
Meanwhile, violence also continued to stalk Pakistan's biggest city here where four people belonging to the Mehsud tribe were shot dead today.
