A shutter-down strike was observed in Quetta on Friday against the sectarian killing of six Shias the previous day.
On Thursday, unknown attackers had opened indiscriminate fire on a van carrying passengers from the Hazara community in Quetta.
The strike call was given by the Hazara Democratic Party (HDP), Shia Conference and backed by Pakhtunkhwa Milli Awami Party (PMAP), Jamhoori Watan Party (JWP) and other nationalist parties to condemn the incident.
Police and Frontier Corps (FC) were deployed in sensitive areas.
Trade and business activities in Quetta came to a halt and all shops, trading centers, retailers and commercial establishments on Prince Road, Masjid Road, Liaquat Bazaar, Joint Road, Saryab Road, Alamdar Road, Hazara Town, Marriabad, Abdul Sattar Road, Zarghoon Road and others remained closed.
Police rounded up over a dozens of suspects during the search operations for investigation.
Addressing a news conference at Hazara Graveyard, vice president of the Shia Conference said police had rounded up several people of the Hazara community during a peaceful protest.
The Hazara community staged a protest at the graveyard demanding an immediate arrest of culprits involved in targeted killings of the Hazara community.
The angry protestors burnt tyres on Eastern Bypass and raised slogans against the government and law enforcement agencies for their failure to protect the life and property of people.
Balochistan has seen wave of sectarian and targeted killings in recent months.
On March 29, at least eight people, a woman and a policeman among them, were killed and 13 others injured in what appeared to be a sectarian attack on a group of Hazara people and in ensuing clashes between police and protesters.