Jordan on Tuesday charged four men with illegally trying to cross into Syria after an exchange of gunfire with Jordanian border guards last week, a military prosecutor said.

The prosecutor said three of the men were in custody following their arrest along an isolated stretch of the northern frontier with Syria.

He said the fourth man escaped after the group had shot at a Jordanian border patrol, wounding one officer. The prosecutor spoke on condition of anonymity because he was not authorized to discuss an ongoing investigation.

He said the men were all Jordanian and were armed with automatic rifles and ammunition, and had computers and mobile phones when they were arrested.

They were being questioned in custody on whether they planned to join what Western and Jordanian intelligence services estimate to be around 2,000 foreigners fighting alongside Syrian rebels trying to topple President Bashar Assad, the prosecutor added.

The men face up to three years in prison, if convicted, he added.

At the time of the border incident, the leader of Jordan's militant Salafis announced that four fighters had arrived in the Syrian border town of Daraa to fight against Assad. It was not immediately clear if the arrested men were linked to that group.

The Salafi leader, Mohammad al-Chalabi, told The Associated Press that he had no immediate information if any group members were arrested.

Al-Chalabi's ultraorthodox Sunni Muslim group accuses Assad, who is a member of Syria's ruling Alawite minority, of intentionally killing Syrians from the rival Sunni Muslim sect at the behest of Shiite powerhouse Iran. The Alawites are a secret offshoot of Shiite Islam and make up about 15 percent of Syria's 23 million people. Sunnis make up 60 percent of the population.

Western and Jordanian intelligence officials estimate that up to 60 members of al-Chalabi's banned Salafi Jihadi group, which even considers non-militant Sunni Muslims as infidels, are fighting in Syria.

In other developments, about 50 Syrian refugees in Jordan rioted in their desert border camp of Zaatari after a dust storm late Monday that destroyed 100 tents, leaving scores of refugee families out in the night cold.

A Jordanian police official said the refugees torched a private car that belonged to an aid worker and a trailer used to store medical supplies to the 32,000 residents of Zaatari camp. A Syrian refugee said police fired tear gas, causing panic among the refugee families, many of whom already had breathing problems because of the dust storm.

Both the police official and the Syrian refugee said no one was injured. They spoke on condition of anonymity, citing the sensitivity of the refugee issue in Jordan.