In this Wednesday, Aug. 16, 2017 photo, a nurse attends to Argelia Mansio who was injured by a stray bullet during an assault staged by unknown attackers at the Roosevelt Hospital, in Guatemala City. The deputy hospital director told reporters that 12 people were wounded, including a child who underwent surgery and was in critical condition. Luis Soto AP Photo

Based on that paragraph can we conclude that this sentence is true?
The stray bullet was fired by an illegal firearm.