"We're very concerned at the brazen nature of these attacks, and would like to hear from anyone who saw anyone acting suspicious in the Royal Oak area last night," Armstrong said.
"People are entitled to feel safe in their neighbourhoods."
Police have increased patrols in the area in an effort to find the person responsible and prevent further offences.
Armstrong said people could take a few easy steps to help keep themselves safe when out exercising at night time.
"We recommend running in pairs or groups at night time and to have your mobile phone with you," he said.
"Police also advise anyone exercising or walking at night time to stick to well-lit areas for extra security."
Those with information that may help with the investigation in these incidents are being urged to call 09 302 6400 or provide information anonymously to Crimestoppers on 0800 555 111.