Security forces have taken control of the streets of the Mongolian capital, Ulan Bator, after the president declared a four-day state of emergency to quell violent protests over the country's recent elections.

The city was reported to be largely calm on Wednesday, a day after thousands of people took to the streets to protest what they said was widespread vote rigging.

Police had largely sealed off the centre of the capital and a curfew was in force, witnesses said.

Nambaryn Enkhbayar, the Mongolian president, declared a state of emergency late on Tuesday after the headquarters of the ruling party was torched by protesters.

State television reported that at least four people were killed and hundreds of policemen were injured in clashes that continued well into Tuesday night.

Mongolian National Broadcasting (MNB) quoted a doctor at a local hospital as saying that two of the four people had been shot dead.

The state-run channel also said that 400 policemen had been injured.

The president has promised to investigate "any irregularities during the election", according to the website Mongolia News.

Police used tear gas, rubber bullets and water cannon to beat back violent protesters who fought police and smashed their way into the headquarters of the ruling Mongolian People's Revolutionary Party (MPRP).

Local journalist Irja Halasz told Al Jazeera that protesters kept restarting fires that had been extinguished and stopped fire fighters from getting close. She said they also hurled stones to push back the police line.

The offices of the General Election Commission were also attacked by protesters on Tuesday night, demanding that officials resign over alleged voting irregularities.

There were also reports of looting in an art gallery and government offices during the protests.

Al-Jazeera