The glowing lava that lit up the night sky could be seen from 72 kilometers away.
Three fissures have now opened in the rock, but according to geologists, the lava still poses no danger to nearby communities.
The US Geological Survey warns, however, that Mauna Loa is a dynamic volcano – meaning that new fissures may appear.
Winds can also carry volcanic gas and ash down the mountain.
Authorities have still not issued an evacuation order, but the volcano's summit and several roads in the region have been closed.
Shelters have also been opened as a precautionary measure.
Hawaii is home to six active volcanoes, including Mauna Loa – the world's largest active volcano – which has erupted 33 times since 1843. The last eruption was in 1984.