Activists say at least 21 people have been killed in Daraa, southern Syria, after an explosion struck a vehicle travelling through Tel al-Juma at midnight last night.
The Syrian Observatory for Human Rights said four children and six women were among the dead. Activists in the area accused the military of planting a bomb.
Deraa was were the birthplace of the Syrian uprising against President Bashar Assad started in March 2011.
The family of a British man thought to have been killed in Syria have told ITV News they were shocked to know he had travelled there.
Syrian state television showed pictures of the British passport of 22-year-old Ali Al Manasfi and said he was shot by President Assad's forces.
ITV News Correspondent Neil Connery reports.
It is believed that Ali Al Manasfi is the British man killed by forces loyal to President Bashir al-Assad.
ITV News believes the man shown on Syrian state television to be Ali Al-Manasfi. SANA TV in Syria have shown images of a British passport and claim that the man shown was among three Westerners killed by forces loyal to Basha al-Assad.
Syrian state TV has released pictures of the bullet ridden car three Western "fighters" were said to be travelling in when they died in Idlib, northwest Syria.
The broadcaster said the trio were carrying rifles, ammunition, grenades and the flag of al-Nusra, an al-Qaida affliated group.
The family of the 33-year-old woman who died in Syria whilst reportedly fighting for opposition forces said she converted to Islam after meeting and marrying an Arab immigrant.
Monica Mansfield Speelman, Nicole Mansfield's aunt, told The Detroit Free Press she converted to Islam after her marriage and started wearing an hijab, which "bothered" her family.
Her grandmother Carole Mansfield said Nicole was adamant about her new way of life, telling them:
The couple then divorced "about three years ago" after the man was able to get a green card that allowed him to stay in the US, according to her aunt.
Syrian state television broadcast images of the passport of an American woman they say was killed by government forces.
SANA TV said Nicole Mansfield and two other westerners working with rebel fighters were killed whilst travelling near the border with Turkey.
The Foreign Office is investigating reports that a Briton has been killed by government forces in Syria. A spokesperson said:
A 33-year-old woman from Michigan has been killed fighting for the Syrian opposition, according to her family.
Nicole Mansfield, a single mother of an 18-year-old from Flint in Michigan had converted to Islam about five years ago, her aunt told Reuters.
The FBI informed the family on Thursday that she had died. Her aunt, Monica Mansfield Speelman, said: