The FBI is investigating a reported sexual assault aboard the Carnival Breeze cruise ship that took place in late-July.

Passengers on the ship told said they woke up to the sound of sirens at around 3 or 4 a.m. Wednesday, and one heard a request for medical assistance on one of its decks, according to KHOU.

The FBI’s Houston field office is “aware of an incident” that took place around July 23 aboard the Carnival Dream, the agency said.