- Two people were killed and more than 20 injured as gunfire broke out at a demonstration
- The protesters want autonomy for south Yemen and oppose the upcoming presidential election
- President Ali Abdullah Saleh is due to step down after the February 21 vote
- His vice president is campaigning for election, although powers have already passed to him
Two people were killed Thursday as hundreds of demonstrators marched in Yemen's southern province of Dhale protesting the upcoming presidential election, eyewitnesses told CNN.
The demonstrators were from the Southern Movement, which is demanding that south Yemen is granted freedom and becomes a separate state because, activists say, the north has oppressed the south and its people.
The movement rejects any government efforts to keep south Yemen under the united Yemen banner.
Gunmen marching within the demonstrators' ranks attacked a government election building, demanding that it be closed down, four eyewitnesses told CNN.
Two security officials in Dhale, who could not be named because they are not authorized to speak to the media, told CNN that two people were killed in the clashes and more than 20 injured. Among those killed was a child who was hit by a stray bullet.
The gunmen fired hundreds of rounds at government buildings, forcing the march to disperse.
Central Security forces responded and clashes continued for more than three hours.
One of the security officials said gunmen with links to the Southern Movement wanted to cause chaos to prevent elections from taking place.
He said the security forces were given orders to be very cautious when dealing with those who oppose the election and to use force only when being attacked. The authorities want to ensure the election takes place successfully, he said.
On Tuesday, extremist factions within the Southern Movement called for a boycott of the February 21 presidential election.
Yemeni Vice President Abdurabu Mansur Hadi has said he is running for president in that election, although powers have already been passed to him from President Ali Abdullah Saleh and he is the only candidate.
Under a plan forged by the Gulf Cooperation Council, Saleh -- who's been in office for 33 years -- will step down after the election and will receive immunity from prosecution.
Executive powers have already been transferred to Hadi. The power transfer deal, signed in November, states that Saleh's deputy will succeed him in power for a term of two years.
However, Hadi has insisted on holding an election on the grounds that his presidency is not official unless he is chosen by the people. Launching his presidential campaign Tuesday, he said he was seeking a new direction for the country.
Saleh is currently seeking medical treatment in the United States for wounds he suffered in an assassination attempt in the presidential palace in June 2011.
The nation has been wracked by unrest, including protests against Saleh, since early last year, when pro-democratic uprisings spread across the Arab world.