A large plume of steam is emitting from the top of the Mount St. Helens volcano in the northwest United States, and scientists say an eruption is likely.
Geologists say a small amount of ash appears to be escaping the volcano along with the steam. They say small earthquakes continue to shake the area in Washington state.
Earlier, scientists said there were signs that molten rock was moving underground and building pressure inside the mountain.
A volcano alert for Mount St. Helens is at the highest level, and people have been told to leave the immediate area.
Scientists say they expect any new volcanic eruption to be smaller than the 1980 explosion that killed 57 people.