Pakistani police say that Baluch demonstrators have burnt dozens of shops, banks and government vehicles in Quetta, the provincial capital of Baluchistan and in other cities since Bugti's death was announced on Saturday evening.
Suleman Sayed, Quetta's police chief, said that more than 450 rioters had been arrested by Sunday morning. Nine policemen have been injured by demonstrators.
The protests began after Pakistan's army killed Bugti in a raid on his mountain hideout on Saturday.
Bugti had campaigned, politically and then militarily, for Baluchs to receive a greater share of the money produced by Baluchistan's natural gas fields, Pakistan's largest.
An alliance of four Baluch nationalist groups have announced a 15-day mourning period to commemorate Bugti and said that protests throughout the region would continue.
Businesses and public transport will observe a strike on Monday, they said.
"The government has pushed Baluchistan into a never-ending war," said Hasil Bizinjo, a senior figure of Baluch Yakjehti, or the Baluch Solidarity alliance.
Baluch separatist movements have been demanding greater autonomy from Islamabad for more than 30 years and clashes between armed Baluch nationalist groups and the Pakistani army are common.
In an attempt to end the unrest, the police declared an indefinite curfew in Quetta early on Sunday morning.
But by midday violence was reportedly continuing in Quetta and had spread to Karachi, Pakistan's main port city, and other towns and cities.
Rioters have mainly targeted government property
In northern Quetta nine policemen were injured when 70 protesters, some firing pistols, tried to loot a bank and several nearby shops, said police inspector Zahir Shah. Police fired tear gas to disperse them, he said.
In the southern port of Karachi, large numbers of Baluch people pelted cars with stones and set tyres alight, police said. Extra police and paramilitary forces have been deployed to the city's streets.
A bomb also damaged a government building and a telephone exchange was set on fire in Kalat, a town about 250km (155 miles) south of Quetta, Ghulam Farid Jamali, a police officer said.
No casualties were caused by the blast or fire, he said.
Amanullah Kanrani, a former senator in Bugti's Jamhoori Watan, or Democratic Nation Party, said the Baluch struggle for greater autonomy would continue despite the tribal chief's death.
"The whole Baluch nation is still alive and people have the same sentiments as Nawab Akbar Bugti," said Kanrani, a long-time ally of Bugti.
The Pakistani military killed Bugti and at least 20 of his followers several days after a bomb, allegedly laid by Bugti's followers, blew up an army vehicle and wounded four soldiers in nearby Kohlu district.
The government had also accused Bugti of ordering attacks on government installations, including gas refineries, the electricity grid and train lines.