Search operations are continuing for three people after a landslide occurred in a residential area in Matsuyama City in the western Japanese prefecture of Ehime.

Local authorities say the slope of a mountain, with Matsuyama Castle at its summit, collapsed just before 4 a.m. on Friday. The collapsed area was 50 meters wide and 100 meters high. The resulting landslide caused mud to enter houses and apartment buildings at the foot of the mountain.

They also say three people, who were believed to have been living in a wooden two-story house hit by the landslide, remain unaccounted for. They are a man in his 90s, a woman in her 80s and a man in his 40s.

About 170 firefighters and police officers are searching for them.

The search is reportedly proving difficult due to a massive amount of mud that has entered the house.

It will continue through the night while ensuring safety, as rain is expected to intensify again.

After the landslide, the city issued the highest-level evacuation alert for about 22,000 people in more than 13,000 households. Residents were urged to move to safer places and take actions that could increase their chances of survival.

As of 8 a.m. on Friday, Matsuyama City had recorded 213 millimeters of rainfall since Wednesday. The amount is almost equal to the average for the entire month of July.