The Isle of Man TT has suspended the Sidecar class from the remainder of this year's meeting after early crashes.
The Crowe brothers are in hospital with head injuries, while Maria Costello and Shaun Parker were also hospitalised, after crashing in Sidecar machinery.
The Crowes' incident in the Sidecar qualifying session prompted a red flag which ended Wednesday's action on the course. Driver Ryan and passenger Callum crashed after Crosby leap on their first lap.
Ryan is "conscious and talking, and he has been taken to Noble's Hospital by ambulance for further assessment of injuries," a statement from the TT confirmed.
Callum is "conscious and talking" and is also in hospital for treatment on his injuries.
Their team Crowe Racing posted to social media: "Both Ryan and Callum are receiving care at Noble's Hospital for fractures and head injuries. While they are currently sedated to allow further checks to be carried out, we understand there is no immediate risk to their lives."
The Crowe brothers, legends of the Sidecar category at the TT, had already gone fastest in the previous qualifying session before their incident.
Ryan and Callum, from the Isle of Man, are the lap record holders in a Sidecar (121.022mph).
Maria Costello 'serious but stable'
Maria Costello was airlifted to hospital while her passenger Shaun Parker was taken by ambulance after their incident earlier in the week.
Costello has since been transferred to Aintree Hospital and is "serious but stable," a statement from the TT confirmed. She continues to be assessed and treated for injuries.
Parker is "conscious and talking" while injuries to his chest, leg, arm and face are treated.
Sidecar class suspended at Isle of Man TT
The TT organisers have opted to stop any further Sidecar sessions this year after an an "immediate technical and operational review."
It is described as a precautionary measure in the interests of competitor and spectator safety.
"This decision has not been taken lightly," a statement from the organisers added.
Dean Harrison, Michael Dunlop top timesheets at Isle of Man TT
Dean Harrison is the fastest rider in the Superstock qualifying session, clocking 133.712mph on his Honda Racing machine.
He said: "We've made a few tweaks to the Superbike to make it a bit easier to ride but the sun will be difficult, so the plan is to have two steady laps."
Michael Dunlop registered his fastest-ever lap on a Sportbike (123.557mph on a Paton).
Dunlop was then fastest in the Supersport class (129.557mph).
Channing Tatum spotted riding at Isle of Man TT
Hollywood star Channing Tatum was spotted at the TT.
The actor is making a movie about the famous motorsport event which is produced by Brad Pitt. It will accompanies by a documentary called The Greatest Show on Earth which was filmed two years ago.
Tatum shot scenes for the movie in the crowds of spectators, and on a bike at the start line.