(CNN) -- Syrian security forces fired on protesters in a show of force after Friday prayers in Daraa, leaving at least 22 unarmed civilians dead, a doctor told CNN.

But official Syrian news had a different account, saying 19 security forces were killed and dozens of others were injured in violence caused by "armed groups" firing at citizens and "unarmed security forces."

A tense calm settled on the restive southern city as night fell, but it seethed over the bloodshed and conflict. Mosques announced the names of the dead and burial times over the quiet and empty streets.

"Daraa is now the city of ghosts," the doctor said.

Daraa was one of several cities where protests took place Friday. Others occurred near Daraa and in Latakia, Banias, Qamishli, Homs, Douma, Moathamia, Daraya, Tal, and Hama.

The violence drew widespread and international condemnation.

"It is time for the Syrian government to stop repressing its citizens and to listen to the voices of the Syrian people calling for meaningful political and economic reforms," U.S. President Barack Obama said in a statement.

Amnesty International said unarmed people calling "for greater freedoms were reportedly attacked by security forces firing live ammunition."

"The alarming reports coming from Syria today show that the authorities have not altered their violent methods for dealing with dissent," said Philip Luther, deputy director of the Middle East and North Africa Program at Amnesty International.

British Foreign Secretary William Hague condemned "the killing of demonstrators by the Syrian security forces" and said he's been concerned about the violence in the country, including in Daraa.

"The Syrian government must uphold its responsibility to protect demonstrators and respect the right of peaceful protest and free speech. The Syrian government should address the legitimate demands of the Syrian people. Political reforms must be brought forward and implemented without delay," he said in a statement.

The Syrian Arab News Agency, or SANA, said 19 security forces were killed and 75 were injured, citing an official source. It said security forces in Daraa were instructed not to carry weapons, and that armed groups fired on citizens and unarmed police when people left the Omari Mosque after prayers.

According to SANA, the source said gunmen fired at an ambulance carrying injured people to a hospital and killed the driver. The people threw stones at police and set tires, facilities and cars on fire. Police had to use tear gas to disperse crowds, it reported.

Syria state TV said armed gunmen injured six people in Homs. SANA said people attacked security forces and burned police cars in there.

Reem Haddad, a government spokeswoman, said security forces "were given very strict orders not to use live ammunition and they didn't."

But she claimed that some of the protesters were carrying rifles and guns, a fact she said was confirmed by video on Syrian Arab TV. She said a Syrian TV center in Daraa was attacked.

But activists had a different account of the violence after thousands of people poured out of mosques around the city and headed for the main square in Daraa.

The protesters were chanting for greater political freedom and the release of political prisoners, according to a human rights activist in Daraa who agreed to be identified only by his first name, Mohamad.

Security forces surrounding the square fired on the protesters before they reached the square, a doctor said.

The doctor said the security forces kept physicians from getting to the city's main hospital to tend to the wounded. Gunfire could be heard in the background as the witness spoke to CNN.

The doctor said that along with the dead, more than 40 people were injured, and of the dead, five had been returned to their families for burial. Dozens of people complained of breathing problems from tear gas.

Wissam Tarif, a human rights activist outside Damascus who had received reports about the unfolding violence, said security forces also were arresting protesters.

CNN could not independently confirm the accounts.

Anti-government protests began in mid-March, with unrest first centering in the Daraa region and spreading to other parts of the country.

Scores of people have died, and President Bashar al-Assad's regime has been criticized for the lethal force used against anti-government protesters.

Amnesty International said on Friday that at least 171 people are believed to have been killed during the past three weeks of protest, counting at least six in Daraa and two in Homs, in the west, on Friday.

"Since the first protesters died (in Daraa) on 18 March, Amnesty International has recorded the names, via information received from sources including human rights activists and lawyers, of 171 people killed," it said. "The majority appear to have been killed by live ammunition fired by the security forces."

Haddad mentioned that President Bashar al-Assad has begun "practical steps" for reforms and demands have been addressed.

That "leaves us with the question," she said: "Who are those protesters and why would a citizen with legal and rightful demands burn, destroy and damage public property built with taxpayers money?"

CNN's Salma Abdelaziz and Rima Maktabi contributed to this report.