Mobs wielding bamboo sticks and pipes thrashed supporters of Bangladesh’s toppled ruling party on Thursday, preventing them from gathering for their first major gathering since their leader fled the country.

The attackers, in Dhaka, the capital, were largely supporters of opposition parties that had endured abuse from former Prime Minister Sheikh Hasina’s ruling Awami League. The student protesters who rallied to topple Ms. Hasina have become de facto police offers on the streets, but on Thursday they were mostly on the sidelines, broadcasting pleas for peace and calm that were ignored.

The violence — latest outbreak in the cycle of vengeance that has afflicted Bangladesh through many turbulent periods — highlighted one of the stark challenges facing the new interim government. And there have been other troubling signs that the government will struggle to keep order and bring justice.

In the week since Ms. Hasina was toppled by a student protest movement and fled to India, the purging of the former ruling party from the government has continued. Protesters have continued to call for the former prime minister to face justice for the deaths of about 500 people during the monthlong uprising, most of them in the crackdown that she unleashed.

At least two senior members of Ms. Hasina’s government were arrested by the security forces on Tuesday as they tried to flee the country by boat. When they appeared in court on Wednesday, their opponents prevented their lawyers from defending them, local news media reported, continuing a pattern of injustice that had long bent to those in power.

Bangladesh’s army chief also appeared to be confirming reports that some of the leaders of Ms. Hasina’s party were being housed in its quarters, saying the military would shelter anyone facing threat of “extrajudicial action.”