A volcano on a southwestern Japan island erupted early Friday, sending large rocks almost 1 kilometer from the crater and prompting the weather agency to raise its alert by one level to restrict entry into the area surrounding the mountain.

The eruption occurred at the crater of Mt. Otake on Suwanose Island of Kagoshima Prefecture at around 2:12 a.m. There were no immediate reports of injuries, according to local authorities.

The Japan Meteorological Agency raised its alert level to 3 on a scale of 5, meaning that people should not approach the mountain. The agency also warned of the potential for big rocks to be hurled into the air within about a 2-km radius of the crater of the 799-meter mountain in Toshima village.

According to the agency, multiple explosions occurred at the crater on Thursday. Following the eruption early Friday, the government also set up a liaison office at the prime minister's office to gather information.

Suwanose, a volcanic island with a population of less than 100, is located to the south of Japan's southernmost main island of Kyushu.