Thomas Cook, which has holidaymakers in the resort, said: "Thomas Cook has been advised of an incident that occurred earlier today in Sousse, Tunisia.
"At this time, details are not clear as to which property(ies) have been affected, with conflicting news reports.
"We are currently gathering information and will provide an update as soon as possible. Our teams on the ground are offering every support to our customers and their families in the area.
"We will continue to monitor the situation, working closely with the FCO and local authorities."
Stories continue to emerge of the heroism and compassion of Tunisians who tried to help in the wake of the Sousse attack.
Seifeddine Rezgui was halfway through a Masters degree and took exams at the Institute for Applied Science and Technology before the attack.
As details of the dead continue to surface, James Jordan met Mohamed Sabhi, who ran towards the carnage to shepherd tourists to safety.