Spontaneous student protests are rare in Bangladesh and the government should handle them carefully ahead of elections due by December, said Mahbubur Rahman, a political science professor at Dhaka's North South University. The opposition has denied involvement.
The protests, which began last Sunday after two college students were struck and killed by a pair of buses, have paralyzed Dhaka, a city of 10 million.
Three years in jail is the current maximum in Bangladesh.
The deliberate running over of people will draw murder charges and carry the death sentence, he added.
Activists have also taken to social media in droves to call on local and worldwide media organisations to cover the story.
Defying government warnings to end the protests, some university students on Monday threw bricks at police and others tried to take processions through the city.
Shipping Minister Shajahan Khan questioned the protesters' fury, saying that in neighboring India, a recent crash killed more than 30 people, "but do they talk about it the way we do?"
A auto carrying U.S. ambassador Marcia Bernicat was on Saturday attacked by armed adult men, but she escaped unscathed, the embassy said. "However, two security vehicles sustained some damage".
On security ground, the workers and owners both did not want to run their buses until the situation became "normal" and "safe", he said. The attack came after the U.S. ambassador left the residence of Badiul Alam Majumder, a secretary of a local civil society advocacy group known as Shujan, around 11:00pm (local time) on Saturday.More news: German couple convicted of rape, online sale of young son
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Earlier the embassy had criticized the police crackdown on the protesters, whom it described as having "united and captured the imagination of the whole country".
Police use batons and tear-gas canisters to disperse the crowds.
Police said they had not identified the attackers.
Alam was screaming as he was forced into a vehicle, it quoted security guards at the building as saying.
Now, the government in Bangladesh has reportedly blocked mobile internet in the country in an effort to curb violent protests that are being carried out in the region.
Mr Alam had criticised the government's handling of the protests in interviews with global media.
"There is no justification whatsoever for detaining anyone for exclusively peacefully expressing their views", Omar Waraich, Amnesty's deputy South Asia director, said in a statement.
In some places, there have been clashes between the protesters and police.
"Students and young people have a legitimate right to speak out on issues of concern to them including road safety issues and to have their opinion heard without the threat of violence", it said in a statement on Sunday.