"The cabin crew tried to say a passenger pulled the hatch which everyone denied. They also tried to get us to stop taking videos or pictures."
The flight had just arrived in Abuja from Lagos, Nigeria, when the door fell off.
Passenger Igah Dagogo told CNN he saw that the door was not properly latched before takeoff.
"I was one foot away from the emergency exit door, so I could see the handle was popping out," Dagogo said.
"We informed one of the air hostesses who insisted that it was locked."
When the door fell, it almost hit a man seated nearby, Mr Dagogo said.
"The white man by the door had to shift because the door would have hit him. When he shifted the door now fell on the floor of the plane," he said.
He added: "I wonder what would have happened if the door fell off midair."
Another passenger, Ola Orekunrin, told CNN she noticed the door had been "unstable" for the whole flight.
But Dana Air denied the door fell off as a result of a mechanical issue, and instead blamed "a passenger".
"We wish to state categorically that this could never have happened without a conscious effort by a passenger to open it," the Nigerian airline said in a statement.