At 09:35 BST, the chimps at Twycross Zoo escaped into an area they were not meant to be, leading to safety concerns.
A police spokesperson later said "everything was now in order".
Twycross Zoo, which reopened two hours later, said the animals were encouraged back into their enclosure with ice cream and fizzy drinks.
A zoo spokeswoman said: "At no time were the public at risk, and no people or chimps were harmed during the incident, however it is part of our safety procedures that we close the zoo whilst such events are resolved.
BBC Nature: Chimpanzees
"All of the chimps are fine, if not a little excited about having ice cream for breakfast. They are all on view to the public as normal."
Sharon Redrobe, the zoo's director, told BBC Radio Leicester: "Eight adventurous chimps got into the service corridors, but still within the main building, so it was still reasonably safe.
"They had a fun time running up and down, opening and closing cupboards. It took about an hour to get them into their day place.
"We apologise for closing but it was for a very good reason."
An internal investigation will now take place to discover how the animals escaped.
Leicestershire Police said the problem occurred during the moving of eight chimps and officers were called as a precaution.
A Leicestershire zoo had to close when eight chimpanzees found their way into service corridors in their enclosure.