Gunmen waylaid a minibus south of Kirkuk and seized four Christian men, a church leader said Friday.

Rt. Rev. Louis Saka, the Chaldean Catholic archbishop in Kirkuk, said a 21-year-old Christian woman was in the bus when it was stopped Thursday but was released by the captors, who are demanding a $40,000 ransom.

The group was traveling to the Kurdish part of Iraq when the incident occurred near Tuz Khormato about 88 kilometers (55 miles) south of Kirkuk, the archbishop said.

Thousands of Iraqi Christians have fled their homes the 2003 invasion because of threats by Islamic extremists and criminal gangs.