Four Navy sailors are expecting to be court martialed following allegations that they engaged in group sex with an underage girl.

NBC News has obtained charge sheets showing that four sailors allegedly engaged in sex acts with a girl who is between 12 and 16 years old in September 2017.

The alleged assault took place on Naval Base Kitsap-Bangor in Washington, and the NBC News report says the charging documents do not indicate how the girl arrived at the Naval base.

According to the Navy Times, which first reported the allegations, the Naval Base Kitsap first received a tip about the allegations on September 26, 2017. A hearing to determine if the accused sailors should be court martialed took place only last week. It is unclear why there has been an apparent delay in the reporting of the alleged incident and a formal investigation.

The charging documents reportedly allege that the four sailors discussed the group sex in a “smoke room” and later assaulted the girl “with the door open, and with open recording of the group sex using photography and video equipment.”

Two of the four sailors are accused of child pornography, three are accused of engaging in “group sex” with the girl, and a one is accused of groping the girl and penetrating him with his finger.

However, none of the accused have been formally charged, pending an investigation and a decision to court martial the four men.

“The accused are presumed innocent until proven guilty,” Michael Smith, a spokesman for Submarine Group 9, told the Navy Times.

[Feature image: U.S. Navy photo by Jennifer Hunt/U.S. Navy via AP]