Sudanese police have fired tear gas at protesters who took to the streets in Khartoum calling for President Omar al-Bashir's ouster.
Saturday's confrontation took place after a funeral procession for a man killed in an earlier protest grew into another mass anti-government demonstration.
Sudanese have been staging protests and demonstrations since Monday. Originally targeting a cut in government subsidies that caused a sharp rise in fuel prices, the demonstrations have steadily broadened and grown in size.
The unrest has become one of the most serious challenges to Mr. Bashir since he seized power in 1989.
On Saturday, several thousand protesters swelled the crowd of mourners at funeral rites for a pharmacist killed earlier in the week. Some shouted "Freedom, freedom" as they demanded an end to Mr. Bashir's rule.
Witnesses say security forces have fired live ammunition at crowds of protesters throughout the week. Human-rights groups estimate that government forces shot and killed 50 people during the first days of demonstrations.
Sudanese authorities report 33 deaths, including four protesters who police say were shot by unidentified gunmen on Friday.
The U.S. State Department has condemned what it calls Sudan's heavy-handed and brutal crackdown on protests.
Sudan's fuel crisis began after South Sudan broke away from the Khartoum government and became independent in 2011. The new nation controls about three-quarters of crude oil production facilities in the former unified Sudan.