Two police officers are being investigated over "distressing" social media messages relating to the Shoreham Airshow crash.
Sussex Police said a private online message was allegedly sent to a colleague about Operation Bowdell - the force's response to the disaster.
The recipient immediately reported the incident and the two officers, who are based at Brighton and Hove, are under investigation for gross misconduct by the Professional Standards Department.
Deputy Chief Constable Olivia Pinkney said: "I cannot emphasise how upset I am that we are investigating such an allegation.
"My colleagues have informed the victims' families and apologised to them for the unnecessary distress it will undoubtedly cause them.
"They are disappointed as we all are. Such an allegation impacts on everyone who was affected by the crash and detracts from the professionalism of hundreds of colleagues who have worked so tirelessly on this operation."
Eleven people died in the Shoreham Airshow crash on when a vintage Hawker Hunter vintage plane plummeted to the ground on August 22, hitting vehicles travelling on the A27.
The inquest into the deaths was opened and adjourned at a hearing in Horsham last Wednesday.
Ms Pinkney added: "All our efforts are focused on providing the families with the answers they are looking for.
"I encourage my officers and staff to report any alleged behaviour that is below the standard expected, and that is what has happened here. We need to follow processes in relation to disciplinary matters.
"The officers, who are quite new in service, have not been suspended as I want them to work to earn their pay while this is investigated. In the meantime they have been assigned duties away from public contact."