An anti-government protester waves a Thai national flag during a rally at the Department of Public Works and Town and Country Planning in Bangkok on March 5, 2014. File picture: Chaiwat Subprasom

Bangkok -

Gunmen killed one person and wounded four on Tuesday, in another attack on anti-government protesters in Thailand's long political crisis, authorities said.

The shots were fired in mid-afternoon at a bus and a flatbed truck carrying demonstrators to their encampment in central Bangkok after they had protested at a complex of government offices just north of the city.

The website for Erawan emergency services said three men and two women were shot and one of the men died at a hospital.

The women were on a bus and the men were guards for the protesters who were on a sound truck, said Nasser Yeemah, who heads the self-described guards for the Student and People's Network for the Reform of Thailand protest group. He said he suspected the shots were fired from a tall building alongside the expressway where the vehicles were travelling.

The student network is a militant faction of the People's Democratic Reform Committee, which has been seeking to have Prime Minister Yingluck Shinawatra resign to make way for an interim appointed government to initiate anti-corruption reforms.

Police Major General Anucha Romyanan confirmed the circumstances of the shooting and said it was not immediately known what type of weapon was used.

Protest-related violence has left 24 dead and hundreds hurt since November. - Sapa-AP