Hospital officials and activists said at least 30 have been killed since in street violence, mostly in Khartoum. They spoke on condition of anonymity as they were not authorized to talk to the media.
Protesters torched 20 gas stations in Khartoum and elsewhere, and set fire to several police stations. Stores were looted in several parts of the city. Police fired tear gas in some places.
The Change Now youth movement said security forces killed the demonstrators by firing randomly into crowds, including at two funerals of slain protesters in Khartoum Wednesday night.
"The government deployed large security forces to suppress the protests," spokesman Amgad Farid said by telephone. "Whatever the scale of the crackdown, people will not stop," he added.
Farid, also a member of an umbrella group called the Youth Union for Revolution, said protesters' demands had once been purely political and economic but had escalated since the killings.
"The president must step down and the government must resign," he said, referring to al-Bashir, who has ruled over Sudan for more than two decades. "Now, the demands are retribution for the killings and bloodshed."
An activist in Khartoum's flashpoint Omdurman district said it had been emptied of residents, who fled either out of fear or in preparation of Friday's protests. Violence appeared to hit a lull on Thursday with no deaths immediately reported.
The activist said there were no attacks on gas stations where the army was deployed. He said people are hesitant to engage the military but see the police as their adversary. Long lines stretched outside gas stations and people are upset, but they are calling on the army to side with the protesters.
A resident in Khartoum said Internet had been restored by late afternoon in the capital. The U.S.-based Renesys, a company that monitors the worldwide state of the Internet also said Thursday that the Internet had been restored after almost 24 hours of total blackout.
Last year, an attempt by the government to cut subsidies sparked similar protests but they were quelled by a heavy crackdown on protesters, activists and journalists.
Sudan lost most of its main oil-producing territory when South Sudan broke off and became an independent state in 2011.
The latest riots first began in the state of Gezira, south of Khartoum, and in some places turned into a call for the ouster of al-Bashir.
Al-Bashir is wanted by the International Criminal Court on allegations linked to the conflict in Sudan's western region of Darfur where an estimated 300,000 people have died since 2003 due to fighting between government-backed tribes and rebels.
