PHNOM PENH, Cambodia (AP) — Riot police in Cambodia clashed with hundreds of anti-government protesters in the capital on Sunday, leaving several people injured.

The protesters were demanding the release of 23 other demonstrators who were arrested during a crackdown earlier this month.

When police blocked them from entering the capital’s Freedom Park, protesters hurled rocks, water bottles and shoes toward security forces, who hit back with batons and tasers.

An Associated Press reporter saw at least two injured protesters and police detain two others arrested during a 15 minute clash.

The government imposed a ban on rallies and street marches in the capital, Phnom Penh, after a wave of anti-government protests in early January that posed the biggest challenge in years to the authoritarian rule of Prime Minister Hun Sen, who has ruled the country for almost three decades.

Sam Rainsy, head of the main opposition Cambodia National Rescue Party, said he won’t give up his movement’s struggle until Hun Sen resigns and calls new elections. The opposition says elections in July were rigged and cheated them of victory.

Last week, police briefly detained 11 activists who were trying to hand over a petition to foreign embassies urging them to help free the 23 protesters.