Riot police used tear gas to break up the demonstration.

防暴警察使用了催泪瓦斯驱散示威游行。

《柯林斯英汉双解大词典》

The largest demonstration was in the southern city of Multan, where riot police attacked hundreds of lawyers, leaving some bloodied as they were loaded into police vans.

最大规模的抗议行动发生在南部城市木尔坦。防暴警察袭击了数百名抗议的律师，部分律师在被押入警方车辆时浑身是血。

youdao

It was just some pornographic film that set off a massive riot demonstration attack which killed four Americans.

CENTERFORSECURITYPOLICY: Rep. Peter King: Keeper of the Flame 2012

It was just some pornographic film that set off a massive riot-demonstration-attack which killed four Americans.

CENTERFORSECURITYPOLICY: Center For Security Policy

Hundreds of riot police were ready before the start of the demonstration.

BBC: Clashes as Chile students march for education reform