No-one was badly hurt in the accident, which comes as another embarrassment for organisers already facing safety concerns after the armed robbery of US gold medallist Ryan Lochte and three of his team-mates at the weekend, as well as the robberies of two visiting government ministers.
The aerial camera, encased in a heavy black cover, belonged to the official Olympics broadcast unit and fell about 20 metres after cables snapped, sending screams through the crowd, witnesses and officials said.
"I was looking to the camera … and suddenly I heard a big snap on the cable and the camera came down," said visitor Chris Adams, a member of the British gymnastics delegation.
A Brazilian television news report showed two women looking dazed, sitting on the ground near the camera.
One woman, bleeding from the face as medics arrived, was taken away on a stretcher.
The other walked from the scene wearing a neck brace.
"You could see on their face that they were hurt, but it was lucky that there was nobody else that was there because I think someone would have been killed," Adams said.
A total of four people were taken to hospital after the incident, including two children who had been hit by a cable, a Rio Games official said.
All were expected to be discharged from hospital later today, the official said.
One of the camera's cables had already broken before it fell and a walkway directly beneath had been cordoned off while the Olympic Broadcasting Services (OBS) unit arranged for a cherry-picker to go to the scene and hoist someone up to it, OBS said.
But the camera came down at an angle, falling outside the cordon, said Adams, the British visitor, who was taking pictures of the park at the time.
"There was a lot of medical people and Rio staff around. They were very, very quick, they were excellent."
Another visitor said there were scenes of confusion after the incident.
"I heard a noise, and at first I saw the cable on the ground, and I didn't understand what happened," said Natalia, without giving a surname.
"But I sat under the bridge and I heard a lot of noise, commotion, fire engines arriving and when I came over to this side I was told that a camera had fallen and I saw some women in the emergency vehicles."
A spokesperson for the Games said the OBS has realised the weight of the camera was too much for its supports and tried to isolate the area before it fell.
"They thought the wire could hold for a little bit more," the spokesperson said.
"[But] the camera fell and hit one of the fences that was isolating the area.
"The camera and the fence hit two women. We're still working to get all the information but we think seven people were injured. They are not serious."
Rio organisers have been struggling with a series of security and logistical problems, including the robbery of US gold medallist swimmer Ryan Lochte and three of his team-mates at gunpoint in the early hours of Sunday.
In the first week of the Games, Portugal's visiting education minister was robbed at knife point, bullets flew into the equestrian centre, a Games bus was attacked with stones and the diving and water polo pools turned green with algae.