Hong Kong police groups are urging the city to impose curfews and invoke other powers under a controversial colonial-era emergency law as Chief Executive Carrie Lam struggles to control escalating unrest.

Associations representing front-line officers and inspectors called on the government to take dramatic steps after the city suffered some of its worst violence yet on the National Day holiday Tuesday. Waves of rallies across the former British colony led to widespread clashes between protesters and police, with an officer shooting and wounding a demonstrator for the first time since unrest began almost four months ago.

"In the face of such a massive series of rioting incidents, we cannot work alone without appropriate measures and support from the top level," Junior Police Officers' Association chairman Lam Chi-wai said in a statement. "We are only an enforcement agency with limited power under the law."