AlQa'dah 3, 1434, Sep 9, 2013, SPA -- Gunmen in the northern Iraqi city of Tikrit killed six policemen Monday before hijacking a bus carrying university students whom they left stranded in the desert outside the city, dpa cited police as saying. The gunmen opened fire on traffic police at a junction in the east of the city, 170 kilometres north of the capital Baghdad, killing six of them. They then hijacked a minibus carrying 11 female students, killing the driver before escaping to the desert south of the city where they left the students stranded. The students were rescued after making mobile calls to relatives.