A water main break at the eastern end of the H-1 freeway caused a massive, daylong traffic jam Saturday that spread like octopus tentacles into the side streets of Kaimuki and major arteries such as the Pali Highway.

Police said repairs might take until Monday.

“Use alternate routes,” the Honolulu Police Department urged succinctly in its update just after 5 p.m. Saturday.

At some points during the day, eastbound lanes of the H-1 were backed up for miles.

The trouble began at 4:45 a.m. when a 24-inch transmission line broke on Kalanianaole Highway between Kilauea Avenue and Waikui Street, the Board of Water Supply said.

Police closed the eastbound lanes of the freeway, with traffic turning around at the westbound Kilauea Avenue offramp near Kahala Mall.

The break initially affected customers from Keanu Street in Palolo to Black Point to Ainakoa. However, after crews isolated the damaged section, water service was restored to all but 11 nearby customers, the water board said.

For those customers, the board set up a water wagon at 4494 Aliikoa St.

A paving contractor was brought in to repair the heavily damaged roadway. Initially, the board thought that might allow one lane to be reopened by the end of the day, but later the repair schedule grew uncertain.

“Barring any unforeseen circumstances, we are hoping this can be completed sometime tonight,” board spokeswoman Tracy Burgo said by email Saturday.

At midday, a normally 20-minute trip from downtown to Kaimuki took one motorist about 75 minutes.

Waialae and Harding avenues in Kaimuki were also clogged as a result. The jam extended to the townbound lanes of the Pali Highway, and police at one point were diverting traffic via Waimanalo.

The Safeway and Costco stores in Hawaii Kai, typically filled with shoppers on weekends, had no lines at checkout and plenty of empty parking spaces in the afternoon. Employees at both blamed the traffic woes for the drop in business.