Visitors at the Kansas City Zoo got more excitement than they bargained for Sunday when two gorillas escaped.

The primates got loose inside of a building.  That area was put on lockdown and families were forced to go to a safe spot while workers tried to corner the animals.

The workers came face-to-face with two 400-pound gorillas.

Zoo director Randy Wisthoff says there's a safety door preventing the gorillas from getting to the public, but nobody knew how the apes would react to being in the same room with the workers.

Workers quickly started telling visitors to leave.

Families were moved out of the Africa area of the zoo into safe zones like restaurants.

Nobody was hurt, and after nearly four hours the gorillas were back in their homes.

Zoo officials said the incident started by a zoo worker forgetting to secure a lock.

Officials will review the incident to make sure it doesn't happen again.