Most stores were shuttered Thursday and families collected the dead for burial following riots Wednesday over election results. The government had warned that any more civil unrest would be dealt with sternly.
Security forces opened fire on stone-throwing demonstrators Wednesday, killing at least 26 people, the government said. European Union observers said some opposition politicians were placed under house arrest following the government's victory in last month's election.
"The death toll now stands at 26, after a few injured people died during the night," Information Minister Bereket Simone said Thursday, denying claims of a higher toll.
A senior member of the opposition United Ethiopian Democratic Forces was being held in his office by police, and the top two leaders of the opposition Coalition for Unity and Democracy were under police surveillance, officials said.
Five office workers for the coalition were arrested, party members said, and the Ethiopian Human Rights Commission said two of their investigators were missing.
The European Union expressed "deep concern" about the violence and appealed "to all parties to avoid any incendiary language or action that could lead to further violence."
Taxi and bus drivers as well as shop owners in the capital began a strike Wednesday, after two days of protests that mainly involved students. The strike continued Thursday, despite government threats of retaliation.
"We had thought we were over this kind of violence," said Brahru Zewde, a historian. "After the last two months, when the country has been enjoying open discussions about the elections, this is clearly a setback for all of us."
Although the ruling party has promised democratic reform, it has shown authoritarian tendencies. It claimed victory in May 15 legislative elections, but opponents said the vote was flawed by fraud and violence.