Witnesses called the National Park Service after seeing the Cessna 207 plunge into the lake near the border between Utah and Arizona, the Kane County Sheriff’s Office said in a statement.
The pilot reported engine trouble shortly after taking off from Page, Arizona, the sheriff’s office said.
Witnesses on passing boats worked with the pilot to save four of the passengers from the submerged plane.
They were transported to shore where a helicopter took three with serious injuries to St George Regional Hospital, in Utah.
Two others were taken to Page Hospital by ambulance.
The bodies of two of the tourists were later located in the plane at a depth of 120 feet below the water’s surface. They were recovered with help from the National Park Service and the Utah Department of Public Safety.
Their identities have not yet been released.
The Federal Aviation Administration and National Transportation Safety Board are investigating the cause of the crash.