WASHINGTON — A federal jury has reached a verdict in the case of four Blackwater security guards on trial in the shootings of more than 30 Iraqi citizens.

The shootings in downtown Baghdad shortly after noon on Sept. 16, 2007 triggered an international uproar over the role of defense contractors on urban battlefields.

One former Blackwater guard faced a first-degree murder charge. Three other former Blackwater guards were charged with voluntary manslaughter, involuntary manslaughter and attempted manslaughter. They also faced gun charges.

Lawyers for the defendants said the guards acted in self-defense in firing their weapons.

The maximum sentence for conviction of first-degree murder is life imprisonment. The gun charges carry mandatory minimum prison terms of 30 years.