A group of Iranian pilgrims have been kidnapped in the town of Balad north of the Iraqi capital Baghdad.
The shrine in Samarra is off-limits to Iranian pilgrims
Four men and two women were seized on a pilgrimage to a Shia Muslim shrine in Samarra. The women were released several hours later, police said.
Iranian pilgrims are allowed to visit Iraqi shrines under a deal agreed this year, but they are barred from Samarra because of security threats.
Huge numbers have flooded in since the fall of Saddam Hussein in 2003.
Six of the revered 12 Shia imams - or successors to the Prophet Muhammad - are believed to be buried on Iraqi soil.
Unidentified gunmen opened fire on the pilgrims' minibus, seriously wounding the driver, police said.
Separately, the German government has said it believes a German archaeologist and her driver had been kidnapped in Iraq.
And the British embassy in Baghdad has confirmed that a third British Shia pilgrim, Yehya Gulamali, has died following an attack on a minibus south of Baghdad on Monday.
Four Western aid workers were seized in Baghdad on Saturday, including two Canadians and a Briton.
It is estimated that at least 200 foreigners have been abducted in Iraq over the last 18 months. Some have been executed by their kidnappers.