Fifty-two baboons escaped on Friday from their enclosure at the Paris zoological park in Vincennes, on the southeastern outskirts of the French capital, according to reports.

The zoo has been evacuated, police have arrived and three marksmen armed with hypodermic guns are at the scene.

The latest reports suggest that all but four have now returned to their enclosure after being caught "in a net", according to police sources.

"Our colleagues have them surrounded," one policemen told Le Parisien. Zookeepers and vets were swiftly called in to round them up. "They can be dangerous. They mustn't get out of the park," said the police source.

A security perimeter has been established around the zoo to stop cars from driving in nearby roads.