WASHINGTON ( CNN ) -- Security contractor Blackwater said any guards who acted improperly in a deadly 2007 shooting in Baghdad should be held accountable , but believes its team acted in self-defense , a company spokeswoman said . A woman walks past a burned car in September after an incident involving Blackwater security guards . Officials familiar with the case said Sunday that six Blackwater contractors have been told they face possible charges in the September 2007 shootings in Baghdad 's Nusoor Square . All six received `` target letters '' from the Justice Department , which has convened a grand jury to hear evidence in the case , the officials told CNN . No final decisions have been made , but target letters often signal that criminal charges are in the works . Iraqi authorities have accused Blackwater guards of killing 17 civilians and wounding nearly 30 in the shootings . But Blackwater has repeatedly said its guards were acting `` in response to a hostile threat , '' company spokeswoman Anne Tyrrell said in a written statement late Sunday . `` Since the September 16 , 2007 incident , we have said that , based on statements of company personnel who were directly involved , we believe those involved acted appropriately , '' Tyrrell said . `` If it is determined that an individual acted improperly , Blackwater would support holding that person accountable . But at this stage , without being able to review evidence collected in an ongoing investigation , we will not prejudge the actions of any individual . '' The company has given its full cooperation to the grand jury , which was seated in November , Tyrrell said . Blackwater said its guards were protecting a U.S. diplomatic convoy when they came under fire in Nusoor Square in western Baghdad . But an Iraqi government commission that investigated the shootings accused the guards of firing on civilians indiscriminately . The first U.S. soldiers who arrived on the scene also told investigators they found no evidence the guards were fired upon , sources familiar with the investigation previously told CNN . An estimated 25,000 private security contractors protect diplomats , reconstruction workers and government officials there . Security contractors have had immunity from Iraqi law under a provision put into place in the early days of the U.S.-led occupation of Iraq . The Nusoor Square shootings led to angry protests from Iraq , as well as demands that the contractors face trial in Iraqi courts . CNN Justice Correspondent Kelli Arena contributed to this report .
Blackwater says any guards who acted improperly should be held accountable . Guards receive target letters from Justice Department that often precede indictments . The company has been under fire for its role in the Iraq war, and it was recently accused of killing civilians with a helicopter gunship while on patrol. Witnesses say motorists , children and innocent bystanders among those killed .