AMMAN, Jordan -- The United Nations said Sunday it is alarmed at the "violent nature" of a demonstration in a massive Syrian refugee camp in Jordan that killed one person and wounded dozens.

Saturday's deadly protest in the sprawling Zaatari camp reverberated around the region as international aid agencies and host governments struggle to cope and manage millions of Syrians who have fled the 3-year-old conflict and sought shelter in neighbouring Iraq, Jordan, Lebanon and Turkey.

In a statement, the UN refugee agency said a "heated demonstration" in Zaatari turned to "a violent one" after possibly thousands of refugees started throwing rocks at a police post inside the camp. The protest started over a refugee family being held there after police detained them and a driver who tried to smuggle them out, the UNHCR said.

Police fired tear gas and there were reports of live ammunition being used, the statement said. Three Syrian refugees were sent to hospital with gunshot wounds and one has since died, the UNHCR said. The statement said 28 policemen were wounded in the protest. Nine tents and five mobile homes were burnt, the agency said.

"Tremendous efforts have been made over the past months to create an atmosphere of civility in the camp," the UNHCR said, appealing to the Syrian refugee to "respect Jordanian law."

Earlier, Jordanian police said in a statement that its troops used tear gas to break up crowds who attacked the police station and set fire to tents. Thousands of refugees fled the east side of the camp where the riots broke out, the statement said, adding that 29 policemen were injured.

Brig. Gen. Waddah Hmoud, director of Jordan's Syrian refugee camps affairs department, said a 25-year-old Syrian was killed in the violence and at least two other refugees were wounded.

Jordan is home to 588,979 registered Syrians refugees, and the numbers grow daily.

Most of the Syrians are staying in two organized encampments near the northern border with Syria. With a population exceeding 120,000, Zaatari is the biggest camp. The refugees are under direct care of the United Nations and the Jordanian government. There are an undetermined number of unregistered refugees in Jordan, including many who have moved into the country's towns and cities.

Meanwhile in Syria, rebels fighting to oust President Bashar Assad fired mortars into central Damascus, killing two people near the Opera House, state media said. Rebels around the capital have focused on hitting protected area housing government buildings to relieve pressure on opposition fighters facing a renewed offensive by Assad's forces around Damascus, said an activist who uses the name Muaz al-Shami. He spoke over Skype.

Syrian state news agency SANA said other mortar shells hit nearby areas. On Saturday, mortar fire injured 22 people in the city. The British-based Observatory for Human Rights confirmed both days' shelling.