NEW : Thousands pilgrims killed and many injured in attacks Thursday . `` We are used to bombings . Two of Shiite pilgrims are making their way to Karbala to mark Imam Hussein . Scores of pilgrims have been killed in attacks blamed on Iraqi extremists . Shiite security forces have sealed roads around Karbala .
NEW : Thousands pilgrims killed and many injured in attacks Thursday . Two of Shiite pilgrims are making their way to Karbala to mark Imam Hussein . Scores of pilgrims have been killed in attacks blamed on Iraqi extremists . Shiite security forces have sealed roads around Karbala .