Violent clashes that have killed more than 40 people this week in Ethiopia have spread from the capital to towns outside of Addis Ababa.
Many people have opted to stay at home as security forces patrol
In the capital, one woman was killed in a fourth day of riots between opposition supporters and police.
The BBC's Mohammed Adow says arrests continued overnight with truckloads of opposition supporters being taken out of Addis Ababa.
The opposition resumed protests this week over polls they say were rigged.
These are the worst disturbances in Africa's second most populous country since protests ignited after the May elections, when some 36 people died and hundreds were arrested.
Information Minister Berhan Hailu confirmed that trouble had flared up in other places and that the security forces were working to bring them under control.
Doctors said most of the dead had been shot in the chest
The eastern city of Dire Dawa and southern city of Awassa have experienced unrest as well as the towns of Dessie, Bahir Dar, Gonder and Debre Markos in the Amhara region to the north.
Our correspondent says that reports from Awassa and Bahir Dar indicate that there have been deaths and casualities there, but no figures have been confirmed.
Tour operators denied a report that a tourist bus had been attacked in Bahir Dar .
In the capital, all taxis and most cars are off the streets, which are being heavily patrolled by soldiers in armoured cars, our correspondent says.
Sporadic gunshots were heard as youths tried to stop passengers from using government-owned buses, and a young woman died after she fell from a fast moving bus as it was attacked by protesters.
Schools and most shops remain closed and those supermarkets that are open have long queues forming outside, as people want to stock up in case the unrest continues.
United Nations workers have been advised to remain at home.
"The atmosphere in Ethiopia is not good. I am worried about myself and my family at home," Tafara, a government worker told Reuters.
"We think it could explode any time," he said.
Doctors have told reporters of more than 150 people coming to hospital wounded in clashes this week. Many of those killed had been shot.
Seven police officers are among those killed.
Security officers have arrested all 15 members of the main opposition Coalition for Unity and Democracy (CUD) party's Central Committee, a lawyer for the party says.
The US State Department appealed for calm and urged the government to remove restrictions on political groups, and to appoint an independent commission to examine the cause of the violence.
Meanwhile, The Times newspaper reports that UK MPs have questioned their country's aid budget to Ethiopia, which is heavily dependent on foreign aid.
The CUD resumed protests this week after its members refused to attend parliamentary sessions.
Prime Minister Meles Zenawi's EPRDF won a majority in polls but the opposition gained many seats.
The Ethiopian government has dismissed an assessment by European Union monitors that the elections failed to meet international standards.