There were reports of arrests in Harare, according to nongovernmental organizations.

Cabani Moyo, information officer for Crisis in Zimbabwe Coalition, an alliance of human rights groups, described via cellphone two arrests he was trying to investigate at Harare’s central police station. He said Marvelous Kumalo, an incoming member of Parliament elected from a constituency near Harare, had sent a text messaged to him saying he and Frank Chikore, a freelance journalist, had been arrested and were being held at the station.

Mr. Moyo said Mr. Chikore was arrested Tuesday while videotaping the police in a northern suburb of Harare as they towed away a charred bus. “They ransacked his home, took his videotapes, cameras, cellphones and laptop,” Mr. Moyo said.

Mr. Moyo said Mr. Kumalo had called him on Monday to say that his wife had sent him a text message saying intelligence agents were looking for him in connection with the protest. “Don’t come home,” she instructed him, according to Mr. Moyo.

Later, after visiting the central police station, Mr. Moyo said the police told him and Mr. Kumalo’s wife that the two men were not there. It was not possible to confirm independently whether the two men had been arrested.

A security guard who works in Harare described a panicked phone call he received from his brother, who he said lives in their home village in Nurewa, a rural area east of the capital. A militia of 10 to 15 youths, armed with a gun, knobkerries and batons, had come marauding, said the guard, spoke on condition of anonymity. He said the militia rounded up the villagers and demanded to know who had been putting up posters for the opposition Movement for Democratic Change and campaigning for its candidates.

Half a dozen villagers had been badly beaten, the guard said.

“They are still bringing the violence,” he said. “They are still collecting the names, targeting people so they can beat them. There’s nothing I can do.”

Official results of last month’s voting showed that Mr. Mugabe’s party, ZANU-PF, had lost control of the lower house of Parliament for the first time in 28 years.