HONOLULU (AP) — Thousands of residents in towns north of Honolulu were told to evacuate their homes early Friday morning as flooding from heavy rains intensified and water levels rose behind a 120-year-old dam.

Emergency sirens blared along Oahu’s famed North Shore, where rising waters damaged some homes and vehicles. Honolulu officials issued a “LEAVE NOW” evacuation order at 5:35 a.m. Friday for Waialua and Haleiwa: “Extremely dangerous flooding and Wahiawa Dam is high.”

Officials have been watching dam levels since a storm last week dumped heavy rain across the state, which led to catastrophic flooding that washed away roads and homes. After the worst of it, a similar but weaker storm was forecast to bring more rain through this weekend.

Hawaii Gov. Josh Green said in a social media post that the Hawaii National Guard has been activated to respond to the flooding. “The storm of course is very severe right now, particularly on the northern part of Oahu,” he said, describing chest-high flood waters. “It’s going to be a very touch-and-go day.”

As she prepared to evacuate to a friend’s home on higher ground, Waialua resident Kathleen Pahinui told The Associated Press in a phone interview that the aging dam is a concern every time it rains.

“Just pray for us,” she said. “We understand there’s more raining coming.”