Hundreds of protesters marched along Kalakaua Avenue Sunday morning in opposition to the construction of the Thirty Meter Telescope at Mauna Kea on Hawaii island.

Organizers circulated flyers via social media for the “Waikiki for Mauna Kea” march, with TMT opponents gathering near the intersection of Kalakaua and Kuhio avenues around 10 a.m.

Shortly after 11 a.m., traffic cameras showed hundreds of people in the street. Honolulu Police Department officers responded to help move protesters onto the sidewalk, but traffic quickly backed up along Kalakaua as people made their way to Kapiolani Park near the Honolulu Zoo.

Honolulu police radio traffic indicated more than 1,000 people were in Kapiolani Park around noon Sunday. Traffic in the area was back to normal by 12:30 p.m.