JAKARTA (Reuters) - Seven people have died and two are in critical condition after Mount Sinabung on Sumatra island erupted on Saturday (May 21), said an Indonesian disaster agency official, adding that the army and police are still searching for survivors in the area.

The 2,460-m tall volcano is among the country's most active. When Sinabung erupted in 2014, more than a dozen people were killed and thousands were evacuated. Before recent times, its last known eruption was four centuries ago.

Since a few years ago, the government has imposed several red zones near Sinabung's crater, including the village of Gamber where the nine people were found, National Disaster Mitigation Agency (BNPB) spokesman Sutopo Purwo Nugroho said in a statement.

"It is not immediately clear how many people were in Gamber because when the mountain spewed clouds of hot ash, there was not supposed to be any activity in the area," Nugroho said on Sunday.

The volcano, about 1,900 km north-west of Jakarta, is still spewing hot ashes as of Sunday, making it dangerous for search and rescue, according to BNPB.

Indonesia, located on the Pacific Rim of Fire, has more than 120 active volcanoes.