TOKYO (AP) — Rescue workers slogged through mud and debris Monday looking for at least 20 people missing since a giant landslide ripped through a Japanese seaside resort town and killed at least three people.

Mud crashed into rows of houses on a mountainside in Atami early Saturday following several days of heavy rains. Witnesses heard a giant roar and then saw the homes swallowed by muddy waves. Bystanders were heard gasping in horror on cell phone videos taken as it happened.

Hundreds of troops, firefighters and other rescue workers toiled in thick mud on the city streets, the scene obscured by continuing rains and fog. Their work was backed by three coast guard ships, and six military drones were being deployed.

Mariko Hattori, an interpreter who lives a short walk away, at first didn’t know what happened. “The first things I noticed were lots of emergency vehicles,” she said. “Then I was frightened when I saw the footage.”

The mudslide struck the Izusan neighborhood, known for hot springs, a shrine and shopping streets in Atami, which is about 100 kilometers (60 miles) southwest of Tokyo.

At an evacuation center, Yuka Komatsu, 47, told the Asahi newspaper she narrowly escaped the mudslide after seeing a nearby apartment building being hit. Frightened, she grabbed her mother and jumped into her car. In the rearview mirror, she saw muddy water swelling and coming from behind as it washed down broken trees and rocks.

“I wonder what happened to our house,” she said.

Three people have been found dead as of early Monday, Fire and Disaster Management Agency and local officials said. Twenty-three people stranded by the slide have been rescued, including three who were injured.

Atami officials said 215 people were registered as living in the 130 homes and other buildings damaged by the slide. Initially, 147 of those people were unreachable, but the number has been lowered to 113 as city officials confirmed some had safely evacuated. They are hoping to be able to get in touch with more of them Monday.

Separately, about 20 were believed buried underneath the mudslide, the disaster agency said.

Shizuoka Gov. Heita Kawakatsu told a news conference Sunday that land development upstream may have been a factor in the mudslide. Citing a preliminary examination by drone, Kawakatsu said massive amounts of soil that had been heaped up at the area under development were all washed down.

It wasn't known if the development was the direct cause, but Kawakatsu said he will investigate the land development. Media reports said a planned housing development had been abandoned after its operator had a financial problem.

Associated Press journalists Haruka Nuga and Yuri Kageyama contributed to this report.

Kantaro Komiya is on Twitter https://twitter.com/KantaroKomia

Haruka Nuga is on Twitter https://twitter.com/HarukaNuga