An American language teacher has been shot dead by gunmen in Yemen's second city of Taiz, officials say.
He was deputy director of a Swedish language centre in the city, a security official told the AFP news agency.
The teacher was driving his car when he was fired on by gunmen on motorbike, officials said.
Yemen had experienced nearly a year of unrest before President Ali Abdullah Saleh agreed to step down, at the end of last year, after 33 years in power.
His vice-president, Abdrabbuh Mansour Hadi, took office last month.
The unrest has enabled militant groups linked to al-Qaeda to gain footholds in provinces in the south of the country.
Taiz, some 270km (173 miles) south-west of the capital Sanaa, has been a major centre of opposition to Mr Saleh's leadership, but has not experienced the same level of militant activity as other parts of the south.
A local police source told Reuters news agency that militants linked to al-Qaeda were thought to have carried out the attack.
But Hamoud al-Sufi, governor of Taiz province, told the Associated Press it was not clear who the killers were, adding that an investigation was under way.