"Police requested that people within the nearby stadium be kept inside while the risk to the public was minimised. This has since lifted and people were able to leave the stadium at around 6.15pm."
Waikato Rugby Union spokesman Joel Skulander told Stuff the lockdown was lifted just before the end of the match however stadium officials decided to keep the gates locked for a short period following full-time.
Police said they were following "positive lines of enquiry to locate the offender".